Enantioselective synthesis, chiral memory

Fig. 24 Enantioselective non covalent synthesis of double rosettes exploiting the chiral memory effect. Exchange of chiral barbiturate with the achiral cyanurate occurs faster then racemization by dissociation of the supramolecular structure and allows temporary preservation of the asymmetry instructed in the first diastereoselective step...

Bonache MA, Gerona-Navarro G, Martfn-Martfnez M, Garcra-Lopez MT, Lopez P, Cativiela C, Gonzilez-Muniz R (2003) Memory of chirality in the enantioselective synthesis of P-lactams derived from amino acids. Influence of the reaction conditions. Synlett 7 1007-1011... 

The memory of chirality concept has been employed in a strategy for the synthesis of chiral a,/ -diamino- and a-amino-/ -hydroxy ester derivatives via asymmetric imino-aldol and aldol reactions, starting from protected aminoesters. The route can 0 be extended to the enantioselective synthesis of aziridines. 

Ghorai MK, Ghosh K, Yadav AK. Enantioselective synthesis of a, p-diamino ester derivatives memory of chirality in imino-aldol reactions. Tetrahedron Lett. 2009 50 476-479. 

In addition to the studies mentioned above, chiral alcohols have been used as H-bonding catalysts in a vinylogous aldol reaction of Chan s diene with aldehydes [73], in an enantioselective Strecker reaction [74], and in the enantioselective addition of aza-enamines to imines [75]. Taddol has also found use as a memory of chirality enhancer in the stereoselective synthesis of (i-lactams from amino acid derivatives [76, 77]. 

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