ABSTRACT
Strongly endothermic reactions are frequently unsuccessful in the ground state because the product, B, is kinetically unstable under the conditions required for its formation. There are two ways by which a chiral auxiliary can be attached to a molecule of interest in order to insure that it crystallizes in a chiral space group-covalently and ionically. An example of an ionic chiral auxiliary-mediated solid-state photoreaction in which conformational enantiomerism is responsible for low ees is found in the -oxoamide system. The success of the solid-state ionic chiral auxiliary approach to asymmetric synthesis can be analyzed in both thermodynamic and kinetic terms. Nature is unreliable when it comes to providing chiral space groups for achiral molecules, and the great majority of achiral substances crystallize in centric or otherwise symmetric packing arrangements.
