School of Chemical Sciences, The University of Auckland , 23 Symonds Street, Auckland 1010, New Zealand.
J Org Chem. 2017 Oct 20;82(20):11225-11229. doi: 10.1021/acs.joc.7b01820. Epub 2017 Oct 10.
The stereoselective access to stereotriads as important polyketide building blocks is reported on the basis of the Krische-type hydrogen-mediated syn-crotylation. The products were obtained with an extremely high diastereoselectivity (dr >99:1), and the newly formed syn stereocenters were controlled solely by the chiral catalyst. The stereochemistry was assigned by crystallography and HPLC for both product manifolds. This extension of the burgeoning transfer hydrogen methodology gives divergent asymmetric access to anti,syn and syn,syn polyketide stereotriads from the same α-chiral starting material and avoids potentially epimerizable aldehyde intermediates.
据报道，基于 Krische 型氢介导的顺式 crotylation，可以立体选择性地获得作为重要聚酮基构建块的立体三联体。通过极高的非对映选择性（dr>99:1）获得了产物，并且新形成的 syn 立体中心仅由手性催化剂控制。通过结晶和 HPLC 对两种产物异构体都进行了立体化学分配。这种新兴的转移氢方法的扩展为从相同的α-手性起始原料获得反式，顺式和顺式，顺式聚酮立体三联体提供了不同的不对称方法，并避免了潜在的可外消旋化的醛中间体。
