Meyer Vera J, Ascheberg Christoph, Niggemann Meike
Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen (Germany).
Chemistry. 2015 Apr 20;21(17):6371-4. doi: 10.1002/chem.201500181. Epub 2015 Feb 16.
A formal intermolecular [2+2+2] cycloaddition reaction of enynes to aldehydes is presented, which can be realized in the presence of a simple and benign calcium catalyst. The reaction proceeds with excellent chemo, regio- and diastereoselectivity and leads to a one-step assembly of highly interesting bicyclic building blocks containing up to three stereocenters from simple precursors via a new type of skeletal rearrangement of enynes. The observed diastereoselectivity is accounted for by two different mechanistic proposals. The first one engages mechanistic prospects arising from a gold catalyzed reaction in the absence of the stabilizing gold substituent. The second proposal involves an unprecedented cyclization-carbonyl allene ene reaction-hydroalkoxylation cascade.
本文报道了一种烯炔与醛的分子间[2+2+2]环加成反应，该反应可在简单且温和的钙催化剂存在下实现。反应具有优异的化学、区域和非对映选择性，通过烯炔的新型骨架重排，从简单前体一步组装出含有多达三个立体中心的高度有趣的双环结构单元。观察到的非对映选择性由两种不同的机理推测来解释。第一种涉及在不存在稳定金取代基的情况下金催化反应产生的机理可能性。第二种推测涉及前所未有的环化-羰基联烯烯反应-氢烷氧基化级联反应。
