Synthesis of γ-Azido-β-ureido Ketones and Their Transformation into Functionalized Pyrrolines and Pyrroles via Staudinger/aza-Wittig Reaction
作者:Anastasia A. Fesenko、Anatoly D. Shutalev
DOI:10.1021/jo302724y
日期:2013.2.1
The synthesis includes three-component condensation of acetals of 2-azidoaldehydes with urea or methylurea and p-toluenesulfinic acid in aqueous formic acid followed by reaction of the obtained N-[(2-azido-1-tosyl)alkyl]ureas with sodium enolates of α-functionalized ketones. The azido ketones or their cyclic isomers are transformed into ureido-substituted Δ1- or/and Δ2-pyrrolines viaStaudinger/aza-Wittig
Ortho-metallation reactions of various N-substituted pyrroles
作者:M.E.K. Cartoon、G.W.H. Cheeseman
DOI:10.1016/s0022-328x(00)85849-0
日期:1982.8
Two routes for the preparation of 2,3-disubstituted pyrroles have been explored. The first involves the directed palladation of a 2-dimethylamino-methylpyrrole and the second the lithiation of a 2-oxazolinopyrrole.
3-Arylsulfonyl pyrroles can be readily obtained from 3-Br-TIPS pyrrole via halogen-metal exchange and subsequent sulfonylation. The regioselectivity of the subsequent directed ortho-metallation (DOM) reaction in order to functionalise the C-2 position depends on the nature of the base (LTMP, n- or s-BuLi) and the N-substituent (SEM or Boc) used. The bulk of the N-substituent also strongly influences