New Ring-Expansion Reactions of Hydroxy Propenoyl Cyclic Compounds under Palladium(0)/Phosphine-Catalyzed Conditions

Palladium(0)-catalyzed one-atom ring-expansion of 1-hydroxy-2,2-dialkyl-1-propenoylindan derivatives has been achieved in the presence of P(o-tolyl)₃ giving 2-hydroxy-3,3-dialkyl-2-vinyl-1-tetralone derivatives in excellent yields. This ring-expansion reaction was applied to a 17-(1-oxo-2-propenyl)-β-estradiol derivative and furnished a similar ring-expanded product in an excellent yield.