The first asymmetric [2,3]-sigmatropicrearrangement of achiral allylic amines has been realized by quaternization of the amines with an enantiomerically pure diazaborolidine and subsequent treatment with Et3N. The resultant homoallylic amines were obtained in good yields and excellent ee's. The observed diastereo- and enantioselectivities were rationalized by invoking a kinetically controlled process
Asymmetric [2,3]-Sigmatropic Rearrangement of Allylic Ammonium Ylides
作者:Jan Blid、Olaf Panknin、Peter Somfai
DOI:10.1021/ja0510562
日期:2005.7.1
An asymmetric Lewis acid-mediated [2,3]-sigmatropicrearrangement of allylic amines has been developed, affording the corresponding homoallylic amines in good yield and excellent enantioselectivities. The rearrangement proceeds by complexation of the chiral Lewis acid to the amine followed by deprotonation and rearrangement.
Lewis acid mediated [2,3]-sigmatropic rearrangement of allylic ammonium ylides
作者:Jan Blid、Peter Somfai
DOI:10.1016/s0040-4039(03)00510-0
日期:2003.4
An investigation of the Lewis acid mediated [2,3]-sigmatropicrearrangement of allylic ammonium ylides has been conducted by employing various bases and boron Lewis acids. Using BBr3 together with the phosphazene base 6, various allylic amines could be rearranged in good yields with low to excellent diastereoselectivity.
Lewis Acid Mediated [2,3]-Sigmatropic Rearrangement of Allylic <i>α</i>-Amino Amides
作者:Jan Blid、Peter Brandt、Peter Somfai
DOI:10.1021/jo035618g
日期:2004.4.1
Boron trifluoride and BBr3 mediated [2,3]-sigmatropic rearrangements of allylicα-amino amides have been developed affording secondary amines in good yields. (E)-Crotyl and (E)-cinnamyl α-amino amides 2b and 2c exhibit excellent syn-diastereoselectivity upon rearrangement with either Lewis acid. The allylic amine 2a forms upon treatment with BF3 or BBr3 a five-membered heterocylic complex in which a