In this case the use of allyl ether-protecting groups allowed their removal under
pH neutral conditions. Thus, treatment of 44 with catalytic Pd(0) in the presence of
a polymethylhydrosiloxane–zinc chloride complex (PMHS–ZnCl 2 ) afforded the
spiroacetal core of paecilospirone in good yield, as a 3.5:1 mixture of anomers.
Scheme 12 Brimble et al.’s synthesis of paecilospirone [55]
Scheme 13 Ir/SpinPHOX as catalysts for the synthesis of bis(benzannulated) spiroacetals [56]
200
M.A. Brimble and L.A. Stubbing
pH neutral conditions. Thus, treatment of 44 with catalytic Pd(0) in the presence of
a polymethylhydrosiloxane–zinc chloride complex (PMHS–ZnCl 2 ) afforded the
spiroacetal core of paecilospirone in good yield, as a 3.5:1 mixture of anomers.
Scheme 12 Brimble et al.’s synthesis of paecilospirone [55]
Scheme 13 Ir/SpinPHOX as catalysts for the synthesis of bis(benzannulated) spiroacetals [56]
200
M.A. Brimble and L.A. Stubbing