Hydroxyl-Assisted Carbonylation of Alkenyltin Derivatives: Development and Application to a Formal Synthesis of Tubelactomicin A

Alkenyltin derivatives flanked by a hydroxyl group are subject to methoxycarbonylation when treated with catalytic amounts of Pd(OAc)2 and Ph3As in MeOH under a CO atmosphere; key to success is the use of 1,4-benzoquinone as a stoichiometric oxidant in combination with trifluoroacetic acid as a cocatalyst. The acid lowers the LUMO of the quinone and likely marshals the critical assembly of the substrates. Under the optimized conditions, competing proto-destannation is marginal; the method proved compatible with various (acid sensitive) functional groups and was applied to a short formal total synthesis of the antibiotic tubelactomicin A.