Insertion of Nitriles into Zirconocene 1-aza-1,3-diene Complexes: Chemoselective Synthesis of N-H and N-Substituted Pyrroles
作者:Shasha Yu、Meijun Xiong、Xin Xie、Yuanhong Liu
DOI:10.1002/anie.201407221
日期:2014.10.20
insertion of nitriles into zirconocene‐1‐aza‐1,3‐diene complexes provides an efficient, chemoselective, and controllable synthesis of N‐H and N‐substitutedpyrroles upon acidic aqueous work‐up. The outcome of the reaction (that is, the formation of N‐H or N‐substitutedpyrroles) results from the different cyclization patterns, which depend on the relative stability and reactivity of the enamine–imine
Rapid access to heterobicycles: A novel cationic gold(I)‐catalyzed tandem heterobicyclization and 1,2‐alkyl migration was developed, which provides a rapid, efficient, and stereoselective access to highlysubstitutedfuro[3,4‐c]azepines from simple, readily available 2‐(1‐alkynyl)‐2‐alken‐1‐ones and α,β‐unsaturated imines under mild conditions (see scheme). In contrast, when heteroaryl imines were
快速访问杂环自行车:开发了一种新型的阳离子金(I)催化的串联异双环化和1,2-烷基迁移,可从简单的方法快速,高效且立体选择性地访问高度取代的呋喃[3,4- c ]氮杂环庚烷,在温和条件下容易获得的2-(1-炔基)-2-烯键-1-酮和α,β-不饱和亚胺(参见方案)。相反,当使用杂芳基亚胺时,仅形成直接的正式的[4 + 3]环加合物。
The Reformatskii type reaction of Gilman and Speeter in the preparation of valuable .beta.-lactams in carbapenem synthesis: scope and synthetic utility
作者:Claudio Palomo、Fernando P. Cossio、Ana Arrieta、Jose M. Odriozola、Mikel Oiarbide、Jesus M. Ontoria
DOI:10.1021/jo00285a021
日期:1989.11
Stereoselective synthesis of .beta.-lactams by condensation of titanium enolates of 2-pyridyl thioesters with imines
作者:Rita Annunziata、Mauro Cinquini、Franco Cozzi、Pier Giorgio Cozzi
DOI:10.1021/jo00041a019
日期:1992.7
A mild and versatile one-pot synthesis of beta-lactams has been performed by condensation of the easily generated titantium enolates of 2-pyridyl thioesters with imines employing chiral reaction partners. Both imines obtained from enantiomerically pure alkoxy aldehydes and the enolate derived from 3-hydroxybutyrate showed high diastereofacial preferences, efficiently transferring the stereochemical information to the stereocenters of the azetidinone ring. Advanced precursors of (+)-PS-5, (+)-PS-6, thienamycin, and 1-beta-methylthienamycin were prepared to illustrate the potential of this method. A H-1-NMR study of the enolization process and a tentative rationalization of the stereochemical results are presented.
3-(1′-hydroxyethyl)-2-azetidinones from 3-hydroxybutyrates and n-arylaldimines