Iminium ion cascade reactions: stereoselective synthesis of quinolizidines and indolizidines
作者:Shawn M. Amorde、Ivan T. Jewett、Stephen F. Martin
DOI:10.1016/j.tet.2008.10.074
日期:2009.4
A noveliminiumion cascade reaction has been developed that allows for the stereoselective synthesis of a variety of substituted aza-fused bicycles. The combination of amino allylsilanes and aldehydes (or ketones) was used to synthesize a number of quinolizidines and indolizidines in a one-pot reaction sequence. This technology has been used to effect the facile syntheses of several indolizidine and
A Prins-pinacol rearrangement is the key step in a new method for synthesizing cis-bicyclo[n.4.0]alkanones. The alkenyl acetal rearrangement substrates 1 are assembled from cycloalkanone precursors in four steps (Table 1). Prins-pinacol rearrangement to form cis-bicyclo[n.4.0]alkanones 3 is best accomplished by exposure of 1 to 1 equiv of TMSOTf and a proton scavenger (2,6-di-tert-butyl-4-methylpyridine) at -78 degrees C --> rt.