15.01.03 · orgchem / structure

Stereoisomerism: enantiomers, diastereomers, meso compounds, and chiral resolution

shipped3 tiersLean: nonepending prereqs

Anchor (Master): Eliel & Wilen — Stereochemistry of Organic Compounds (Wiley, 1994), Ch. 4–7; Anslyn & Dougherty — Modern Physical Organic Chemistry Ch. 6; Cahn, Ingold & Prelog — Angew. Chem. Int. Ed. 5, 385 (1966)

Intuition Beginner

Stereoisomers are molecules with the same atoms connected in the same order but arranged differently in three-dimensional space. Unit 15.01.01 introduced chirality and the idea that a tetrahedral carbon with four different groups has two mirror-image forms. This unit classifies the relationships between those forms and introduces compounds where symmetry makes things more subtle than the simple "each stereocentre doubles the count" picture.

Enantiomers are a pair of non-superimposable mirror images. Think of your left hand and right hand: identical in every measurement except that they are mirror images. Enantiomers have the same melting point, the same boiling point, the same solubility in achiral solvents. They differ only when they interact with another chiral object: plane-polarised light (they rotate it in opposite directions), a chiral receptor in your body (one binds, the other does not), or a chiral catalyst (one reacts faster than the other).

Diastereomers are stereoisomers that are not mirror images. They arise when a molecule has two or more stereocentres and the configurations differ at some but not all of them. Diastereomers have different physical properties: different melting points, different solubilities, different NMR spectra. This makes them much easier to separate than enantiomers.

A meso compound has stereocentres but is achiral overall because an internal mirror plane cancels the optical activity. The stereocentres are real, but the molecule as a whole is superimposable on its own mirror image. Meso compounds do not rotate plane-polarised light.

Chiral resolution is the process of separating enantiomers from a racemic (50:50) mixture. Because enantiomers have identical physical properties in achiral environments, separating them requires introducing chirality: a chiral resolving agent converts them into diastereomers (which do have different properties), or a chiral chromatography column exploits their different interactions with a chiral stationary phase.

Visual Beginner

Picture a molecule with two stereocentres, C2 and C3. Each can be R or S. Four formal combinations exist:

(2R, 3R) and (2S, 3S) are mirror images of each other. This is an enantiomer pair. They have identical physical properties in achiral environments.
(2R, 3S) and (2S, 3R). If C2 and C3 are in equivalent environments (same substituents, symmetric molecule), these two are the same molecule. Rotating one by 180 degrees gives the other. This is the meso form: it has stereocentres but an internal mirror plane makes it achiral.
Compare (2R, 3R) with (2R, 3S). These are not mirror images and not identical. They are diastereomers. They have different melting points, different solubilities, and different NMR spectra.

The key insight: enantiomer pairs are always matched sets of two. Diastereomers are any two stereoisomers that are not an enantiomer pair. Meso compounds arise when internal symmetry identifies two of the formal $2^{n}$ combinations.

Worked example Beginner

Identifying enantiomers, diastereomers, and meso forms in tartaric acid.

Tartaric acid is HOOC-CHOH-CHOH-COOH. Two stereocentres (C2 and C3) with identical substitution patterns. Four formal combinations:

(2R, 3R)-tartaric acid and (2S, 3S)-tartaric acid are enantiomers. They rotate plane-polarised light in opposite directions with equal magnitude.
(2R, 3S)-tartaric acid and (2S, 3R)-tartaric acid are the same molecule. The molecule has a mirror plane through the C2-C3 bond, so these are one compound: meso-tartaric acid. It has zero optical rotation.
(2R, 3R)-tartaric acid and meso-tartaric acid are diastereomers.

Three stereoisomers total, not four, because the meso form reduces the count by one.

Resolution of a racemic amine by diastereomeric salt formation.

Suppose you have a racemic mixture of (R)- and (S)-1-phenylethylamine. Add (R,R)-tartaric acid (a single enantiomer of a chiral acid). The amine forms salts:

(R)-amine + (R,R)-tartaric acid gives one diastereomeric salt.
(S)-amine + (R,R)-tartaric acid gives a different diastereomeric salt.

The two salts have different solubilities. Crystallise from a suitable solvent: one salt precipitates, the other stays in solution. Filter, then liberate the free amine from each salt with base. The enantiomers are now separated.

Check your understanding Beginner

Exercise (medium, multiple choice).

A racemic mixture of a chiral carboxylic acid is treated with a single enantiomer of a chiral amine. The resulting salts can be separated because:

A. The two enantiomers of the acid become diastereomeric salts with different properties B. The amine selectively reacts with only one enantiomer of the acid C. The racemic mixture spontaneously resolves upon mixing D. The salts are enantiomers with different solubilities

Hint

A chiral resolving agent converts enantiomers into diastereomers. What does that imply about their properties?

Answer

A. Each acid enantiomer forms a salt with the chiral amine. The two salts are diastereomers (not mirror images), so they have different physical properties including different solubilities, which permits separation by crystallisation.

Formal definition Intermediate+

Let $M$ be a molecule represented as a stereochemically annotated graph $G = (V, E, ℓ, χ)$ where $V$ is the set of atoms, $E$ the bonds, $ℓ : V \to A$ assigns element labels, and $χ : V_{stereo} \to {R, S}$ assigns configuration descriptors to the set of stereogenic centres $V_{stereo} \subseteq V$ .

Two molecules $M_{1}$ and $M_{2}$ are stereoisomers if they share the same connectivity graph $(V, E, ℓ)$ but differ in $χ$ or in the spatial arrangement of atoms not captured by $χ$ alone (e.g., alkene geometry, axial chirality).

Enantiomers. $M_{1}$ and $M_{2}$ are enantiomers if $M_{2}$ is the mirror image of $M_{1}$ and $M_{1} \neq ≅ M_{2}$ (non-superimposable). In terms of descriptors, every tetrahedral stereocentre is inverted: if $M_{1}$ has $χ_{1} (v) = R$ at centre $v$ , then $M_{2}$ has $χ_{2} (v) = S$ at the corresponding centre, and vice versa. For alkene-based stereoisomers, each E is replaced by Z and each Z by E.

Diastereomers. $M_{1}$ and $M_{2}$ are diastereomers if they are stereoisomers and not enantiomers. Equivalently, they differ at one or more (but not all) stereogenic elements. Diastereomers have different internal coordinates and therefore different physical properties.

Meso compound. A molecule $M$ is meso if $V_{stereo} \neq = \emptyset$ (it has stereocentres) but $M$ is achiral (superimposable on its mirror image). This occurs when $M$ possesses an improper symmetry element ( $σ$ , $i$ , or $S_{n}$ ) that maps each stereocentre to a counterpart with inverted configuration, cancelling the overall chirality.

CIP rules in detail

The Cahn-Ingold-Prelog system assigns unambiguous priority rankings to substituents at each stereogenic element. The algorithm proceeds by recursive comparison of atomic-number lists outward from the stereocentre:

Atomic number. Higher atomic number of the atom directly bonded to the stereocentre receives higher priority.
Recursive expansion. If two directly bonded atoms are the same element, expand one bond further. At each equivalent atom, list the atomic numbers of its other neighbours in descending order and compare the lists lexicographically.
Multiple bonds. A double bond to atom X is treated as two single bonds to a phantom duplicate of X. A triple bond to X is treated as three single bonds to phantom duplicates.
Isotopes. If the above steps fail to distinguish two substituents, compare isotopic mass: higher mass = higher priority (deuterium outranks protium).

The algorithm is guaranteed to terminate because molecular graphs are finite and the substituent trees eventually differ or are identical.

R/S assignment. Orient the stereocentre so the fourth-priority substituent points away from the observer. Trace the arc from first to second to third priority. Clockwise = R, counterclockwise = S. If the fourth-priority group points toward the observer, the reading is inverted.

E/Z assignment. For a double bond C $_{a}$ =C $_{b}$ , rank the two substituents at each carbon by CIP priority. If the two higher-priority substituents are on the same side, the descriptor is Z (zusammen); if on opposite sides, E (entgegen).

Specific rotation and racemic mixtures

The specific rotation $[α]$ quantifies optical activity:

[α]_{λ}^{T} = \frac{α}{c \cdot l},

where $α$ is the observed rotation in degrees, $c$ is concentration in g/mL, and $l$ is path length in decimetres. The sign (+ or -) indicates the direction of rotation: + is dextrorotatory (clockwise facing the source), - is levorotatory (counterclockwise). There is no general correspondence between R/S and +/-.

A racemic mixture (racemate) is a 1:1 mixture of both enantiomers. The net optical rotation is zero because the two equal and opposite rotations cancel. The enantiomeric excess (ee) measures departure from the racemate:

ee = \frac{∣ [ α ] _{obs} ∣}{∣ [ α ] _{pure} ∣} \times 100%.

Pseudoasymmetric centres

A pseudoasymmetric centre is a stereogenic centre whose inversion does not produce a new enantiomer but instead generates a diastereomer. Such centres arise in molecules with two identically substituted but stereochemically distinct branches. The stereogenic atom is labelled $r$ or $s$ (lowercase) by the CIP system to distinguish it from true chiral centres (uppercase R/S). Pseudoasymmetric centres contribute to stereoisomer count without contributing to overall molecular chirality.

Key mechanism Intermediate+

Diastereomeric salt formation for chiral resolution.

Resolution by diastereomeric salt formation exploits the fact that enantiomers, when combined with a chiral resolving agent, become diastereomers with different physical properties. The mechanism proceeds in four stages:

Stage 1: Salt formation. A racemic acid $(\pm)$ -HA is combined with a single enantiomer of a chiral base $(+)$ -B. Two salts form:

(+) -HA \cdot (+) -B and (-) -HA \cdot (+) -B .

These two salts are diastereomers. They have different crystal lattice energies and therefore different solubilities.

Stage 2: Crystallisation. The solution is cooled or concentrated. The less soluble diastereomeric salt crystallises preferentially. The more soluble salt remains in the mother liquor. The degree of separation depends on the solubility ratio of the two salts, which is governed by the difference in lattice enthalpy.

Stage 3: Filtration and liberation. The crystallised salt is filtered off. Treatment with a strong acid or base liberates the free enantiomerically enriched acid or base. The mother liquor yields the opposite enantiomer by the same treatment.

Stage 4: Recrystallisation. The enriched product is recrystallised to increase enantiopurity. Each recrystallisation step removes residual diastereomeric impurity.

The maximum theoretical yield for a single resolution step is 50% of each enantiomer with 100% ee. In practice, yields of 30--40% at 90+% ee are typical for a well-optimised resolution. The efficiency of a resolution is quantified by the resolving power $S$ , which depends on the solubility product ratio of the two diastereomeric salts:

S = \frac{K _{sp} ( more soluble salt )}{K _{sp} ( less soluble salt )} .

A resolving power $S > 5$ is considered practical; $S > 20$ is excellent.

Chromatographic resolution operates on the same principle. A chiral stationary phase provides a diastereomeric interaction environment. The two enantiomers form transient diastereomeric complexes with the stationary phase, leading to different retention times and baseline separation.

Kinetic resolution uses a chiral catalyst that reacts faster with one enantiomer than the other. The rate ratio $k_{fast} / k_{slow} = s$ (the selectivity factor) determines the maximum ee achievable at a given conversion. At 50% conversion, the remaining substrate has ee = $(s - 1) / (s + 1) \times 100%$ .

Exercises Intermediate+

Exercise 3 (medium, short-answer).

Draw all stereoisomers of 2,3,4-trihydroxypentanedioic acid (HOOC-CHOH-CHOH-CHOH-COOH). Identify any meso forms and state the total number of stereoisomers.

Hint

Three stereocentres (C2, C3, C4). C2 and C4 are in equivalent environments (both bonded to COOH and OH). Check for internal mirror planes through C3.

Answer

Three stereocentres give $2^{3} = 8$ formal combinations. C2 and C4 are equivalent, so internal mirror-plane reductions occur. The combinations where C2 and C4 have opposite configurations with C3 in either state produce meso forms: (2R,3R,4S) = (2S,3R,4R) and (2R,3S,4S) = (2S,3S,4R). These two meso forms are diastereomers of each other. The remaining four combinations give two enantiomeric pairs: (2R,3R,4R)/(2S,3S,4S) and (2R,3S,4R)/(2S,3R,4S).

Total: four distinct stereoisomers. Two meso compounds and two enantiomeric pairs.

Exercise 5 (hard, short-answer).

Prove or disprove: a molecule with two stereocentres and a plane of symmetry must be meso.

Hint

A meso compound has stereocentres and is achiral. Consider whether the mirror plane necessarily relates the two stereocentres to each other, or whether it could pass through a stereocentre.

Answer

False as stated. The plane of symmetry must map each stereocentre to a stereocentre with opposite configuration for the molecule to be meso. If the plane passes through both stereocentres (both lie in the mirror plane), the molecule may be meso only if each stereocentre individually has a configuration consistent with the mirror plane -- but a stereocentre lying in a mirror plane requires two of its four substituents to be mirror-related, which makes those substituents equivalent and the centre non-stereogenic. The correct statement is: a molecule with two stereocentres is meso if and only if the two centres are related by an improper symmetry element (mirror plane or inversion centre) that maps one to the other with configuration inversion. A mirror plane that does not relate the two centres (e.g., a plane perpendicular to the line connecting them) does not produce a meso compound.

Exercise 6 (hard, short-answer).

Explain why chiral HPLC can separate enantiomers even though enantiomers have identical physical properties. What is the physical origin of the different retention times?

Hint

The stationary phase is chiral. What kind of interaction does each enantiomer have with it?

Answer

Chiral HPLC uses a stationary phase composed of a chiral selector molecule (e.g., a cellulose derivative or cyclodextrin). Each enantiomer of the analyte forms a transient diastereomeric complex with the chiral stationary phase. These diastereomeric complexes have different binding affinities (different free energies of adsorption), so one enantiomer spends more time adsorbed on the column and elutes later. The separation exploits the diastereomeric relationship between the two analyte-stationary-phase complexes, not any inherent difference between the free enantiomers. The chromatographic resolution is entirely analogous to diastereomeric salt resolution: the chiral environment converts an enantiomeric pair into diastereomeric pairs with different physical properties.

Point group analysis for chirality Master

A rigorous test for molecular chirality uses point group symmetry. A molecule is chiral if and only if its point group contains no improper rotation axis $S_{n}$ (including the special cases $S_{1} = σ$ , a mirror plane, and $S_{2} = i$ , an inversion centre). The chiral point groups are:

$C_{n}$ : a proper rotation axis with no mirror planes
$D_{n}$ : a proper rotation axis with perpendicular $C_{2}$ axes but no mirror planes
$T$ , $O$ , $I$ : the pure rotational (chiral) tetrahedral, octahedral, and icosahedral groups

A molecule in any point group that contains $σ$ , $i$ , or $S_{n}$ ( $n \geq 3$ ) is achiral. This is a complete and sufficient test: it is both necessary and sufficient for chirality determination. The test applies regardless of the source of chirality (tetrahedral centre, axis, plane, or helix).

Point group assignment procedure. Identify the highest-order proper rotation axis. Check for perpendicular $C_{2}$ axes. Check for mirror planes ( $σ_{h}$ , $σ_{v}$ , $σ_{d}$ ). Check for $S_{n}$ axes. The presence or absence of these elements uniquely determines the point group and therefore the chirality.

Examples.

(R)-Lactic acid ( $CH_{3} -CHOH-COOH$ ) has point group $C_{1}$ (no symmetry elements other than identity). $C_{1}$ is chiral.
Meso-tartaric acid has point group $C_{s}$ (a mirror plane through the C2-C3 bond bisecting the molecule). $C_{s}$ contains $σ$ and is achiral.
(R)-BINOL has point group $C_{2}$ (a twofold axis along the biaryl bond). $C_{2}$ is chiral.
[6]Helicene has point group $D_{2}$ (three mutually perpendicular $C_{2}$ axes, no mirror planes). $D_{2}$ is chiral.

Axial chirality: allenes and biaryls Master

Allenes. A cumulated diene C=C=C has two perpendicular $π$ -systems. The central carbon is sp-hybridised, and the substituent planes at the two terminal carbons are mutually perpendicular. When each terminal carbon bears two different substituents, the molecule is chiral despite having no tetrahedral stereocentre. The chirality axis passes through the three carbons of the allene. The two enantiomers differ in the handedness of the screw formed by the perpendicular planes.

Stereochemical descriptor for allenes: view along the chirality axis. Trace the arc from the higher-priority substituent on the near carbon to the higher-priority substituent on the far carbon. Clockwise = $a R$ (axial R); counterclockwise = $a S$ (axial S). The CIP priorities are assigned at each terminal carbon independently.

The enantiomerisation barrier for allenes is very high because interconversion requires passing through a linear transition state. Allenes with different substituent pairs at each terminus are configurationally stable at room temperature.

Axially chiral biaryls (atropisomers). Two aromatic rings linked by a single bond are chiral when large ortho substituents restrict rotation and the two rings are differently substituted. The chirality axis is the biaryl bond. The rotational barrier $Δ G_{rot}^{‡}$ determines configurational stability: a barrier above approximately 22--24 kcal/mol gives a racemisation half-life exceeding 1000 seconds at 298 K, sufficient for isolation.

BINOL (1,1'-bi-2-naphthol) is the archetypal axially chiral biaryl. The peri-hydrogens at the 8-positions prevent coplanarity, and the two atropisomers (aR and aS) are stable. BINAP, the bisphosphine analogue, is among the most widely used chiral ligands in asymmetric catalysis.

Planar chirality Master

Planar chirality arises when a dissymmetric group is attached to a planar, symmetric structure and the spatial relationship between the group and the plane creates non-superimposable mirror images. The chirality plane is the plane of the symmetric ring or fragment, and the chirality is determined by which side of the plane the substituent occupies relative to a designated direction.

[2.2]Paracyclophanes. Two benzene rings bridged by two-carbon chains in forced parallel proximity. When one ring carries a single substituent, the molecule is chiral because the substituent's position relative to the other ring is non-superimposable on its mirror image. The descriptor assigns $R_{p}$ or $S_{p}$ by a CIP-based rule: identify the chirality plane, designate an entry atom on the plane nearest the substituent, and trace the priority arc.

Planar-chiral ferrocenes. Ferrocene has two parallel cyclopentadienyl rings. When one ring carries two different substituents in a 1,2-pattern, the molecule is chiral. Ferrocene-based planar-chiral ligands (Josiphos, Taniaphos) are used industrially in asymmetric hydrogenation.

Topicity: enantiotopic and diastereotopic Master

Topicity classifies the relationship between chemically equivalent groups within a single molecule. Two identical groups (e.g., the two hydrogens on a -CH $_{2}$ - group) may be homotopic, enantiotopic, or diastereotopic.

Homotopic groups are related by a proper rotation ( $C_{n}$ ). Replacing either group produces the same compound. Homotopic groups are chemically equivalent in all environments and have identical NMR chemical shifts.

Enantiotopic groups are related by an improper rotation ( $S_{n}$ , including $σ$ and $i$ ) but not by any proper rotation. Replacing either group produces a pair of enantiomers. Enantiotopic groups are chemically equivalent in achiral environments but become distinct in chiral environments (chiral solvent, chiral catalyst, enzyme active site).

Diastereotopic groups are not related by any symmetry operation. Replacing either group produces a pair of diastereomers. Diastereotopic groups are chemically distinct in all environments, including achiral solvents, and have different NMR chemical shifts.

NMR distinction. The two protons on a -CH $_{2}$ - group adjacent to a stereocentre are diastereotopic and appear as two separate signals (an AB quartet) in the proton NMR spectrum, even in an achiral solvent. This is the most common experimental signature of diastereotopicity and is a direct consequence of the fact that the two protons occupy diastereomeric positions in the molecular framework.

Re/Si face designation for prochiral trigonal centres. A carbonyl group C=O presents two faces. Assign CIP priorities to the three substituents at the trigonal carbon. View from one face: if the arc 1-2-3 is clockwise, the face is Re; if counterclockwise, Si. In a molecule with an existing stereocentre, the two faces of a carbonyl are diastereotopic, and nucleophilic attack on each face gives diastereomeric products with different energies. This facial selectivity is the basis of substrate-controlled diastereoselectivity (Cram's rule, Felkin-Anh model).

Connections Master

Structure and stereochemistry 15.01.01. This unit extends the chirality and CIP framework from the foundational stereochemistry unit into a complete taxonomy of stereoisomer relationships (enantiomer, diastereomer, meso) and resolution methods.
Conformational analysis 15.01.04 pending. Ring-flip processes in cyclohexane and other rings generate diastereomeric conformers. The enantiomer/diastereomer classification developed here is needed to analyse the stereochemical consequences of ring flips.
Substitution mechanisms 15.04.02. SN2 produces inversion at a single stereocentre (switching one enantiomer to the other). SN1 produces racemisation (a 50:50 mixture of enantiomers). These outcomes are direct applications of the enantiomer concept.
Alkene addition reactions 15.05.01. Electrophilic addition to alkenes creates new stereocentres. The products are classified as enantiomers or diastereomers depending on the stereochemistry of the starting material and the syn/anti nature of the addition.
Carbonyl chemistry 15.07.01. Nucleophilic addition to a chiral aldehyde generates diastereomeric products. The Felkin-Anh model predicts which diastereomer predominates based on the existing stereocentre.

Historical notes Master

The classification of stereoisomers into enantiomers and diastereomers emerged gradually after van't Hoff and Le Bel independently proposed the tetrahedral carbon in 1874. Van't Hoff recognised that a carbon bonded to four different groups could exist in two non-superimposable mirror-image forms, but the systematic taxonomy of stereoisomer relationships took decades to formalise.

The term "enantiomer" (from Greek enantios, opposite) was introduced by Lord Kelvin in 1904. "Diastereomer" followed, designating stereoisomers that are not mirror images. The systematic classification of stereoisomers by their symmetry relationships (enantiomeric pairs related by mirror symmetry, diastereomers related by no symmetry operation, meso compounds possessing an internal mirror plane) was codified by Eliel and Wilen in their 1994 monograph Stereochemistry of Organic Compounds, which remains the standard reference.

Pasteur's 1848 resolution of sodium ammonium tartrate by manual crystal sorting was the first chiral resolution. The method of diastereomeric salt formation, still the most widely used resolution technique, was developed in the late 19th century and systematised by Pope and Peachey in 1899. The use of chiral chromatography for enantiomer separation dates to the 1960s, with major advances in the 1980s following the development of commercially available chiral stationary phases by Pirkle, Okamoto, and others.

The Cahn-Ingold-Prelog priority rules (1966) provided the algorithmic foundation for unambiguous assignment of R/S and E/Z descriptors, replacing the older D/L system for sugars and amino acids and the ambiguous cis/trans notation for alkenes. The CIP system is a complete and consistent nomenclature: every stereogenic element in a molecule can be assigned a descriptor, and the descriptor set uniquely identifies the stereoisomer.

The concept of pseudoasymmetric centres was introduced by Cahn, Ingold, and Prelog in their 1966 paper to handle the stereochemically nontrivial case where a centre is stereogenic (inversion changes the molecule) but not chirogenic (the inversion produces a diastereomer, not an enantiomer). The lowercase $r$ / $s$ notation distinguishes these from true R/S centres.

The formal connection between point group symmetry and chirality (a molecule is chiral if and only if its point group lacks any improper rotation axis) was established within the framework of mathematical group theory applied to molecular symmetry, as systematised by Cotton's Chemical Applications of Group Theory (1963).

Bibliography Master

Founding papers and monographs.

Cahn, R. S., Ingold, C. K. & Prelog, V., "Specification of Molecular Chirality", Angew. Chem. Int. Ed. 5 (1966), 385--415.
Prelog, V. & Helmchen, G., "Basic Principles of the CIP-System and Proposals for a Revision", Angew. Chem. Int. Ed. 21 (1982), 567--583.

Comprehensive references.

Eliel, E. L. & Wilen, S. H., Stereochemistry of Organic Compounds (Wiley, 1994), Ch. 4--7.
Clayden, J., Greeves, N. & Warren, S., Organic Chemistry, 2nd ed. (Oxford UP, 2012), Ch. 14--16.
Anslyn, E. V. & Dougherty, D. A., Modern Physical Organic Chemistry (University Science Books, 2006), Ch. 6.

Resolution methods.

Pope, W. J. & Peachey, S. J., "The Application of Powerful Optically Active Acids to the Resolution of Externally Compensated Bases. Resolution of Tetrahydroquinaldine", J. Chem. Soc., Trans. 75 (1899), 1066--1077.
Jacques, J., Collet, A. & Wilen, S. H., Enantiomers, Racemates, and Resolutions (Wiley, 1981).

Topicity and prochirality.

Hanson, K. R., "Applications of the Sequence Rule. I. Unique Numbering and Pairing of Saturated Stereoisomeric Molecules and Sites", J. Am. Chem. Soc. 88 (1966), 2731--2742.
Mislow, K. & Raban, M., "Stereoisomeric Relationships of Groups in Molecules", Top. Stereochem. 1 (1967), 1--38.

Prerequisites

15.01.01 pending

Used in

15.01.04

Tier anchors

beginner: Clayden, Greeves & Warren — Organic Chemistry 2nd ed. Ch. 14 (Stereochemistry)
intermediate: Clayden, Greeves & Warren — Organic Chemistry 2nd ed. Ch. 15–16 (Stereochemistry, stereoselectivity); Eliel & Wilen — Stereochemistry of Organic Compounds, Ch. 4–7
master: Eliel & Wilen — Stereochemistry of Organic Compounds (Wiley, 1994), Ch. 4–7; Anslyn & Dougherty — Modern Physical Organic Chemistry Ch. 6; Cahn, Ingold & Prelog — Angew. Chem. Int. Ed. 5, 385 (1966)

References

Clayden, Greeves & Warren — Organic Chemistry, 2nd ed. (Oxford UP, 2012) · Ch. 14–16 (stereochemistry, stereoselectivity, conformational analysis)
Eliel, E. L. & Wilen, S. H. — Stereochemistry of Organic Compounds (Wiley, 1994) · Ch. 4–7 (configuration, conformation, chirality, stereoisomer classification)
Anslyn, E. V. & Dougherty, D. A. — Modern Physical Organic Chemistry (University Science Books, 2006) · Ch. 6 (stereochemistry)
Cahn, R. S., Ingold, C. K. & Prelog, V. — Specification of Molecular Chirality (Angew. Chem. Int. Ed. 5, 385, 1966) · Originator paper for the CIP priority rules

Estimated time

beginner: 20m
intermediate: 45m
master: 90m