Radical coupling of -ketoesters and amides promoted by Brønsted/Lewis acids.

Recent advances in photocatalysis have enabled radical methods with complementary chemoselectivity to established two electron bond forming approaches. While this radical strategy has previously been limited to substrates with favorable redox potentials, Brønsted/Lewis acid activation has emerged as a means of facilitating otherwise difficult reductions. We report herein our investigations into the Lewis acid-promoted redox activation of -ketocarbonyls in a model photocatalytic radical alkylation reaction.

Organocatalytic Mukaiyama Mannich Reactions of 2,5-Bis(trimethylsilyloxy)furan.

The organocatalytic synthesis of densely substituted mono- and bis-γ-lactams involving the Mukaiyama Mannich addition of 2,5-bis(trimethylsilyloxy)furan to imines is described. Use of a ditoluenesulfonylimide catalyst produces γ-lactams from monoaddition, whereas a more acidic catalyst (triflic acid) produces fused bis-lactams from double addition. Optimized organocatalytic conditions allow for the selective synthesis of either desired core as well as the one-pot, multicomponent assembly of the trisubstituted monolactams from aldehydes, amines, and bis-trimethylsilyloxyfuran.

Diastereoselective Base-Catalyzed Formal [4 + 2] Cycloadditions of N-Sulfonyl Imines and Cyclic Anhydrides.

A diastereoselective base-catalyzed Mannich reaction of cyclic, enolizable anhydrides and N-sulfonyl imines for the synthesis of δ-lactams is reported. This anhydride Mannich reaction tolerates imines derived from aryl and enolizable aldehydes. A base-catalyzed product epimerization pathway ensures high anti diastereoselectivity in aryl and achiral enolizable imines.

Enantioselective synthesis of (+)-malbrancheamide B.

The asymmetric total synthesis of the chlorinated [2.2.2]-diazabicyclic indole alkaloid (+)-malbrancheamide B is reported.

Efficient entry to the [2.2.2]-diazabicyclic ring system via diastereoselective domino reaction sequence.

A domino reaction sequence involving aldol condensation, alkene isomerization, and intramolecular hetero-Diels-Alder cycloaddition for the synthesis of [2.2.2]-diazabicyclic structures is reported.