Concise Synthesis of Complicated Polypropionates through One-Pot Dissymmetrical Two-Directional Chain Elongation
Herein, a major breakthrough in a sulfur dioxide-mediated oxyallylation cascade reaction is reported that allows the preparation of complex long-chain polyketide fragments with more than ten stereogenic centers through a carefully designed desymmetrization process. An allylbissilane is combined, under the appropriate reaction conditions, with two different 1,3-dioxy-1,3-dienes permitting the construction of a 13-membered polypropionate precursor in one pot. Four stereocenters are selectively created during this process. The so-obtained pseudo-C-2- or -C-S-symmetric products are desymmetrized through selective deprotection and can be selectively elongated in both directions using aldol chemistry.
Keywords: aldol reaction ; allylsilanes ; asymmetric synthesis ; polyketides ; sulfur dioxide ; tandem reactions ; Diels-Alder Addition ; Asymmetric-Synthesis ; Sulfur-Dioxide ; Absolute-Configuration ; Polyketide Synthesis ; Directed Reduction ; Building-Blocks ; Assignment ; Fragments ; Allylsilanes
Record created on 2011-12-16, modified on 2016-08-09