One-pot preparation of pyrrole derivatives via the copper-catalyzed [4+1] annulation of propargylic amines with ethyl glyoxylate and phenylglyoxal in the presence of piperidine
We describe how copper(II) chloride efficiently catalyzes the [4+1] annulation of propargylamines with either ethyl glyoxylate or phenylglyoxal functioning as a C1 unit, in the presence of piperidine, which leads to a straightforward and one-pot preparation of pyrrolederivatives. The key feature in this annulation is the in-situ generation of an N,O-hemiacetal intermediate from either the glyoxylate
Total Syntheses of (−)-Hanishin, (−)-Longmide B, and (−)-Longmide B Methyl Ester <i>via</i> a Novel Preparation of <i>N</i>-Substituted Pyrrole-2-Carboxylates
作者:Guolin Cheng、Xinyan Wang、Hailin Bao、Chuanjie Cheng、Nan Liu、Yuefei Hu
DOI:10.1021/ol203433c
日期:2012.2.17
N-substituted pyrrole-2-carboxylates has been developed based upon 1,3-dipolar cycloaddition and a conventional hydrogenolysis. By using this method as the key step, totalsyntheses of natural alkaloids (−)-hanishin, (−)-longmide B, and (−)-longmide B methyl ester were accomplished in the highest overall yields, respectively.