| alpha-Acylvinyl anions are atypical nucleophiles that generate valuable alpha,beta-unsaturated carbonyl compounds in a highly convergent manner. This dissertation describes the development and application of silyloxyallenes as alpha-acylvinyl anion equivalents. These previously underutilized silyl allenol ethers are demonstrated to undergo additions to aldehydes, Michael acceptors, and imines. The reactions provide highly functionalized alpha,beta-unsaturated carbonyl compounds in good to excellent yields and with superb control of the resulting alkene geometry. Notably, stereoselective additions for each of the transformations are achieved allowing access to optically active substrates.;The methodology developed is subsequently applied toward the total syntheses of secalosides A and B. The secalosides are tumor cell growth inhibitory glycosides isolated from the rye pollen Secale cereale. Utilizing a reaction sequence involving asymmetric alpha-acylvinyl anion addition followed by intramolecular Heck cyclization, the indan core of secalosides A and B is efficiently synthesized from a racemic silyloxyallene. Coupling strategies for the completion of the syntheses are detailed. |
