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
Isothiocyanate Strategy for the Synthesis of Quaternary α-Amino Acids Bearing a Spirocyclic Ring System
作者:Sebastian Frankowski、Tadeusz Gajda、Łukasz Albrecht
DOI:10.1002/adsc.201701642
日期:2018.5.2
isothiocyanates derived from α‐substituted α‐aminoacids are useful building blocks in the heteroannulation reactions with electron‐deficient olefins. The developed strategy proceeds in a cascade manner and involves Michael addition followed by a cyclization via nucleophilic addition. Target, spirocyclic heterocycles bearing either a quaternary α‐aminoacidmoiety or α‐aminophosphonate group have been