A Mitsunobu-based procedure for the preparation of alkyl and hindered aryl isocyanates from primary amines and carbon dioxide under mild conditions
作者:Michael J Horvath、Dilek Saylik、Patricia S. Elmes、W.R. Jackson、Craig G. Lovel、Keith Moody
DOI:10.1016/s0040-4039(98)02312-0
日期:1999.1
A Mitsunobu-based procedure for the preparation of alkyl and hindered aryl isocyanates in excellent yields fromprimaryamines and carbon dioxide under very mild conditions is described.
Preparation of Isocyanates from Primary Amines and Carbon Dioxide Using Mitsunobu Chemistry<sup>1</sup>
作者:Dilek Saylik、Michael J. Horvath、Patricia S. Elmes、W. Roy Jackson、Craig G. Lovel、Keith Moody
DOI:10.1021/jo982362j
日期:1999.5.1
Primary alkylamines 1 and hindered arylamines 1 give high yields of isocyanates 5 when reacted with carbon dioxide and the Mitsunobu zwitterions 4 generated from dialkyl azodicarboxylates and Bu3P in dichloromethane at -78 degrees C. Use of Ph3P still gave high yields of isocyanates from reactions of primary alkylamines, but only low yields were obtained from reactions of aromatic amines. Reactions which failed to give high yields of isocyanates gave either carbamoylhydrazines 6 and/or dicarbamoylhydrazines 10 and/or triazolinones 7. The triazolinones were shown to arise from reactions of reactive aryl isocyanates with the Mitsunobu zwitterion. The carbamoylhydrazines were shown not to arise from reaction, of isocyanate with reduced dialkyl azodicarboxylates, and a mechanism for their formation is proposed. Single-crystal X-ray analyses confirmed the structures of 6, 7, and 10.
Stereospecific formation of equatorial diacetylimides from the stereoisomers of six-membered carbocyclic amines