Trisubstituted gem-dimethyl alkene

Selenium dioxide reveals a useful stereoselectivity when applied to trisubstituted gem-dimethyl alkenes. The products are predominantly the Zs-allylic alcohol or... 

The first total syntesis of cristatic acid, a potent antibiotic against Gram-positive bacteria, was reported by A. Furstner et al." " The prenylated aromatic substrate (trisubstituted gem-dimethyl alkene) was subjected to a Se02-catalyzed allylic oxidation to obtain stereospecifically the ( )-allylic alcohol. 

The lactone-directed intramolecular Diels-Alder cycloaddition was the key step in D.F. Taber s synthesis of trans-dihydroconfertifolin. During the endgame, the Simmons-Smith cyclopropanation was utiiized to install the gem-dimethyl group at C4. The trisubstituted alkene was cyclopropanated in excellent yield and the resulting cyclopropane was subjected to catalytic hydrogenation. 

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