Aziridines are important synthetic Intermediates which readily undergo ring-opening reactions. It is demonstrated that electron-rich phosphines are efficient catalysts for the regioselective rearrangement of N-acylaziridines to oxazolines. The reactions occur in excellent yield under neutral conditions. Evidence is provided for an addition/elimination mechanism by generation of a phosphonium intermediate. Similar intermediates may be useful for the development of alternate aziridine ring-opening processes and stereoselective synthesis with enantiopure phosphines.
作者:Allen Martin、Kathleen Casto、William Morris、Jeremy B. Morgan
DOI:10.1021/ol202410v
日期:2011.10.21
Aziridines are important synthetic Intermediates which readily undergo ring-opening reactions. It is demonstrated that electron-rich phosphines are efficient catalysts for the regioselective rearrangement of N-acylaziridines to oxazolines. The reactions occur in excellent yield under neutral conditions. Evidence is provided for an addition/elimination mechanism by generation of a phosphonium intermediate. Similar intermediates may be useful for the development of alternate aziridine ring-opening processes and stereoselective synthesis with enantiopure phosphines.
Enantioselective Synthesis and Stereoselective Ring Opening of<i>N</i>-Acylaziridines
作者:Jennifer Cockrell、Christopher Wilhelmsen、Heather Rubin、Allen Martin、Jeremy B. Morgan
DOI:10.1002/anie.201204224
日期:2012.9.24
Kinetic resolution of N‐acylaziridines by nucleophilic ringopening was achieved with (R)‐BINOL as the chiral modifier under boron‐catalyzed conditions (see scheme; Ar=3,5‐dinitrophenyl). The consumed enantiomer of aziridine can be further converted to an enantioenriched 1,2‐chloroamide with recovery of (R)‐BINOL.