Modified Guanidines as Potential Chiral Superbases. 2. Preparation of 1,3-Unsubstituted and 1-Substituted 2-Iminoimidazolidine Derivatives and a Related Guanidine by the 2-Chloro-1,3-dimethylimidazolinium Chloride-Induced Cyclization of Thioureas
作者:Toshio Isobe、Keiko Fukuda、Tatsuhiro Tokunaga、Hiroko Seki、Kentaro Yamaguchi、Tsutomu Ishikawa
DOI:10.1021/jo000745n
日期:2000.11.1
Simple preparation methods for modified guanidines were explored for new chiral superbases, Thus, (4S,5S)-4,5-diphenyl- and diastereomeric cyclohexane-fused 2-iminoimidazolidines were prepared from (1S,2S)-1,2-diphenylethylenediamine and (1R,2R)- or (1S,2S)-1,2-diaminocyclohexanes through cyclization of protected thiourea intermediates with 2-chloro-1,3-dimethylimidazolinium chloride (DMC) as a key reaction. In the (4S,SS)-4,5-diphenyl series 1-methyl-2-iminoimidazolidines and 2-diethylaminoimidazoline were also prepared as related guanidines.