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Utilization of the industrial waste material benzyl (all-R)-cyclopenta[b]pyrrol-2-carboxylate l a or its derivatives lb, l c as chiral auxiliaries is described. Allylation of nitrothioacetamides, proceeding by initial S-allylation followed by a facile thio Claisen rearrangement, is accomplished with a diastereomeric ratio (dr) up to 85:15 using l a , b as auxiliaries in stoichiometric amounts. Another aspect of this report is the diastereoselective synthesis of optically active amines, starting from aldehydes, with optical purities (op) up to 99%. Again a derivative of l a was used as source of chirality. One of the most convincing methods for creating a new asymmetric center in a predictable configuration is the use of [3,3] sigmatropic rearrangements. The reason is that in such intramolecular rearrangements the favorable transition-state geometry can normally be predicted on the basis of the principles of conformational analysis [3].We were encouraged by the high distereoselectivity obtained with an (5')-proline derivative under remote stereocontrol of the thio Claisen rearrangementL41 using S-allylated derivatives of nitrothioacetarnide~[~~l. Therefore several other chiral auxiliaries were screened for chiral induction studies.

1995 cleavage reactions, decomposition reactions, pyrolysis cleavage reactions, decomposition reactions, pyrolysis O 0100 -061Facile Acid-Catalyzed Ring Cleavage of N-Acylated Lactams.-N-acyllactams are successfully cleaved by reaction with alcohols in the presence of an acid to produce the corresponding esters in good yields and excellent regioselectivity. -(DIXIT, A. N.; TANDEL, S. K.; RAJAPPA, S.; Tetrahedron Lett. 35 (1994) 33, 6133-6134; Div. Org. Chem. Synth., Natl. Chem. Lab., Pune 411 008, India; EN)