A concise synthesis of the functionalized [5–7–6] tricyclic skeleton of guanacastepene A
摘要:
The six membered ring of guanacastepene A was constructed by a Diels-Alder reaction of 1,1,4-trisubstituted diene to set up the correct relative stereochernistry at the C8 quaternary center and the remote C5 stereocenter. In 10 efficient steps from the Diels-Alder adduct 9, the desired highly functionalized [5-7-6] tricyclic skeleton 2 was synthesized. Key steps involve trimethylsilyl chloride (TMSCl) assisted Michael addition to form enol ether and the usage of the enol ether in the following intramolecular Mukaiyama aldol reaction to form the middle seven membered ring of guanacastepene A. (C) 2004 Elsevier Ltd. All rights reserved.
An Oxidative [2,3]-Sigmatropic Rearrangement of Allylic Hydrazides
作者:Benjamin F. Strick、Devon A. Mundal、Regan J. Thomson
DOI:10.1021/ja2066219
日期:2011.9.14
The development of an efficient oxidative [2,3]-sigmatropicrearrangement of allylic hydrazides, via singlet N-nitrene intermediates, is reported. The requisite allylic hydrazide precursors are readily prepared and undergo smooth sigmatropic rearrangement upon exposure to iodosobenzene. The products of this novel transformation are shown to be useful precursors to a variety of compounds.
Highly efficient palladium-catalyzed hydrostannation of ethyl ethynyl ether
作者:Ian P. Andrews、Ohyun Kwon
DOI:10.1016/j.tetlet.2008.09.147
日期:2008.12
The palladium-catalyzed hydrostannation of acetylenes is widely exploited in organic synthesis as a means of forming vinyl stannanes for use in palladium-catalyzed cross-coupling reactions. Application of this methodology to ethyl ethynyl ether results in an enol ether that is challenging to isolate from the crude reaction mixture because of incompatibility with typical silica gel chromatography. Reported