Asymmetric α-Chloroallylboration of Amino Aldehydes: A Novel and Highly Versatile Route to <scp>d</scp>- and <scp>l</scp>-<i>erythro</i>-Sphingoid Bases
作者:Christian Hertweck、Wilhelm Boland
DOI:10.1021/jo990117+
日期:1999.6.1
Serinal-derived vinyloxiranes represent versatile building blocks for synthesis of D-(or L-)erythrosphingosine and, its analogues. Asymmetric alpha-chloroallylation of the Garner aldehyde with chiral and achiral gamma-(Z)-chloroallylboranes, followed by DBU-mediated cyclization of the corresponding chlorohydrins, provides a highly effective route to oxazolidine vinyloxiranes in high yield under mild conditions, Matched and mismatched cases of the double diastereoselective allylation were investigated. The vinyloxirane reacts with a variety of organocuprates by a S(N)2' type nucleophilic substitution, yielding protected sphingoid bases as (E)-allylic alcohols exclusively. By the new approach, a multitude of different; sphingoid core structures becomes available, from a uniform protocol, with high yield and efficiency.