Wang et al. [56] have recently described the use of Ir/SpinPHOX catalysts 47
and 48 for the synthesis of bis(benzannulated) spiroacetals under asymmetric
hydrogenation conditions (Scheme 13). Treatment of a variety of substituted
Scheme 14 TMSI-promoted spirocyclization of dihydroxyketones
Scheme 15 Dehydrative spirocyclization in Brimble et al.’s synthesis of γ-rubromycin [61]
Synthesis of 5,6- and 6,6-Spirocyclic Compounds
201