An efficient asymmetric cyclization reaction of amino-acid-derived isothiocyanates with azodicarboxylates is described. The chiral 1,2,4-triazolines are prepared in good yield (up to 87%) and enantioselectivities (up to 95% ee).
An efficient DMAP catalyzed tandem aldol/imidization reaction of alpha-isothiocyanato esters with alpha-ketoamides is described, affording ring-fused thiocarbamates bearing contiguous quaternary carbon centers with up to 99% yield in a completely diastereoselective fashion. This method has a wide range of substrate scope and can be used in the synthesis of pyrrolidines. (c) 2013 Elsevier Ltd. All rights reserved.
FURUKAWA, ISAO;ABE, NOBORU;HASHIMOTO, SHIZUNOBU, NIPPON KAGAKU KAJSI,(1989) N, S. 822-825