Department of Chemistry , University of Houston , Houston , Texas 77204-5003 , United States.
Org Lett. 2018 Jul 6;20(13):3723-3727. doi: 10.1021/acs.orglett.8b01146. Epub 2018 Jun 13.
A chiral auxiliary-based diastereoselective transformation that entirely avoids the stereochemically mismatched pairing, providing equally high levels of asymmetric induction in the formation of each diastereomer is described. In particular, we show that chiral nonracemic methyl ketones undergo α,α-bisalkylation using phenylalanine-derived N-amino cyclic carbamate (ACC) auxiliaries with essentially perfect diastereoselectivity, as well as excellent yield and regioselectivity. Significantly, with the use of a single enantiomer of the auxiliary, either diastereomeric product can be synthesized with an equally high level of asymmetric induction.
描述了一种基于手性辅基的对映选择性转化，该转化完全避免了立体化学不匹配的配对，在每个非对映异构体的形成中提供了同样高水平的不对称诱导。特别是，我们表明，使用苯丙氨酸衍生的 N-氨基环碳酸酯（ACC）助剂，手性非外消旋甲基酮可以进行α，α-双烷基化，具有基本完美的对映选择性，以及优异的收率和区域选择性。重要的是，使用单个辅基的对映异构体，可以以同样高的不对称诱导水平合成两种非对映异构体产物。
