Journal of the American Chemical Society, Vol.131, No.3, 876-876, 2009
Organometallic Enantiomeric Scaffolding. Sequential Semipinacol/1,5-"Michael-like" Reactions as a Strategic Approach to Bridgehead-Quaternary Center Aza[3.3.1]Bicyclics: Application to the Total Synthesis of (-)-Adaline
A nontraditional approach to the enantiocontrolled construction of quaternary center-bearing heteroatom-bridged bicycto[3.3.1]nonanes (homotropanes) is reported that is based on organometallic enantiomeric scaffolding. This strategy takes advantage of the unique reactivity profiles of TpMo(CO)(2)(5-oxo-eta(3)-pyranyl) and TpMo(CO)(2)(5-oxo-eta(3)-pyridinyl) scaffolds, and features a molybdenum-mediated semipinacol/1,5-"Michael-like" reaction sequence to establish the quaternary center and synthesize the bridged bicyclic structure. An asymmetric total synthesis of (-)-adaline highlights this methodology.