Asymmetric Synthesis in the Racemic System

Asymmetric Synthesis in the Racemic System.—Once we had a suitable model system, we moved to the next step of the planning, which required the construction of a crystalline phase isomorphous to (2), but composed of non-chiral molecules or a racemic mixture of molecules. One possible solution to this problem came from the observation that the crystals of many compounds containing the chiral s-butyl group have a strong tendency to disordering about the chiral centre (see Section 4, p. 218). When this is the case, the resolved enantiomer and its racemate generally pack in isostructural crystals. 

With regard to asymmetric synthesis, the main difference between ( + )-(S) (2) and (RS) (2) is that in the former the chirality of the handle defines unequivocally the absolute configuration of the crystalline phase, establishing a finite energy difference between the diastereomeric phases (5 and 5, (and / j and / /), while in the latter the energies of and of R,S, are the same. Since the total enantiomeric 

On the basis of these data, an asymmetric synthesis of chiral dimers and oligomers with quantitative enantiomeric yield is expected in the entire range of solid solubility 

The accomplishment of an absolute asymmetric synthesis with a quantitative enantiomeric yield required at this point a better understanding of the nature of the disordered solid solution of racemic (2) in order to be able to overcome the unfavourable interactions which are responsible for the metastability of this phase this we tried to achieve by different chemical and crystallographic approaches which are described below. 

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