A variety of heterocyclic alcohols and acetates were coupled with silyl ketene acetals and other π-nucleophiles in the presence of trimethylsilyl trifluoromethanesulfonate to provide an array of substituted β-heteroaryl propionates, including those with contiguous quaternary centers, as well as vinylogs thereof. This reaction also proceeds with high diastereoselectivity when the π-nucleophile bears a chiral auxiliary.
The formal syntheses of N-methylwelwitindolinone C isothiocyanate (4) and several other welwitindolinones 5–8 were achieved by the independent synthesis of 79. The synthesis featured a Lewis acid-mediated coupling between a heteroaryl carbinol and bis-TMS enol ether, an intramolecular enolate arylation, and an unprecedented intramolecular allylic alkylation of a γ-acyloxyenone.
The formal syntheses of N-methylwelwitindolinone C isothiocyanate, N-methylwelwitindolinone C isonitrile, N-methylwelwitindolinone D isonitrile, 3-hydroxy-N-methylwelwitindolinone C isothiocyanate, and 3-hydroxy-N-methylwelwitindolinone C isonitrile is reported. The synthesis features several novel processes, including a Lewis acid mediated coupling between a benzylic-type heteroaromatic alcohol and a highly functionalized silyl ketene acetal, an intramolecular enolate arylation, and a regioselective, Pd(0)-catalyzed π-allylic cyclization of a γ-benzoyloxy enone moiety that is revealed by unmasking a furan ring.
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