Prostereoisomerism (prochirality)

Chiral Distortion of Confined Ice Oligomers (n = 5,6)

“…are prochiral. 18 This calls for a chirality measure. 19 The geometric object "triangle" with sides a, b, c, where…”

NMR spectroscopic detection of chirality and enantiopurity in referenced systems without formation of diastereomers

“…discrimination method presented here relies fundamentally on the concept of prochirality41, defined as ‘the geometric property of an achiral object (or spatial arrangement of points or atoms) which is capable of becoming chiral in a single desymmetrization step’42. It is known that when a prochiral compound (for example, an achiral primary carboxylic acid Ph(CH 2 )CO 2 H) is placed in a chiral environment (for example, (+)-(1 R ,2 R )-1,2-diphenylethane-1,2-diamine) forming an acid-amine complex, the enantiotopic (prochiral) methylene hydrogens of the acid exhibit chemical shift non-equivalency and thus are rendered diastereotopic4344. The pro-CSA, H , presented here contains enantiotopic CH reporter groups as shown in Fig.…”

“…More specifically, two onefold improper rotations S 1 (=mirror planes σ d ), which are identical with prochiral planes, can be identified. These mirror planes make group A and B of β-H interconvertible and hence enantiotopic (magnetically equivalent with isochronous NMR resonances)4446.…”

Fundamental Stereochemical Concepts and Nomenclatures

“…In case of the staggered form (the distance between two nearest H atoms on C1 and C2 is 2.5 Å) favorable interaction between the bonding-antibonding orbitals makes its torsional strain 3 kcal/mol less than the eclipsed conformation and makes it more stable. This energy difference leads at 25 C to the fact that for each 160 staggered ethane molecules, there is only one molecule of eclipsed ethane, i.e., in negligible proportion.…”

“…2.11.1) is based on the different behavior of stereoheterotopic ligands and faces in the chemical reactions. The concept of stereoheterotopicity has been discussed in 1967 [22], that of prochirality in 1966 [21], and the topic has been reviewed in detail by Eliel in 1982 [25].…”