Lewis Base Activation of Lewis Acids. Vinylogous Aldol Addition Reactions of Conjugated <i>N</i>,<i>O</i>-Silyl Ketene Acetals to Aldehydes
作者:Scott E. Denmark、John R. Heemstra
DOI:10.1021/ja056747c
日期:2006.2.1
N,O-Silyl dienyl ketene acetals derived from unsaturated morpholine amides have been developed as highly useful reagents for vinylogous aldol addition reactions. In the presence of SiCl4 and the catalytic action of chiral phosphoramide (R,R)-3, N,O-silyl dienyl ketene acetal 8 undergoes high-yielding and highly site-selective addition to a wide variety of aldehydes with excellent enantioselectivity
衍生自不饱和吗啉酰胺的 N,O-甲硅烷基二烯烯酮缩醛已被开发为非常有用的乙烯基醛醇加成反应试剂。在 SiCl4 存在和手性磷酰胺 (R,R)-3 的催化作用下,N,O-甲硅烷基二烯基乙烯酮缩醛 8 以优异的对映选择性与多种醛进行高产率和高位点选择性加成。特别值得注意的是从脂肪醛中获得的高产率和选择性。可以使用低催化剂负载量 (2-5 mol%)。吗啉酰胺可作为进一步合成操作的有用前体。