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A highly regio‐ and diastereoselective 1,4‐addition of azlactones to enones catalyzed by a Brønsted acid is described. The Michael adducts were prepared in moderate to good yields and with complete control of the relative stereochemistry. In addition, two consecutive stereogenic centers were created, one of which was a quaternary stereocenter. The method was successfully extended to the first highly diastereoselective desymmetrization of dibenzylidene acetone.

An innovative method for the methylsulfenylation of electrophilic carbons was explored. Cheap and commercially available dimethyl sulfoxide (DMSO) was used as a source of the –SCH3 group. Chalcone, dibenzylideneacetone, and Morita–Baylis–Hillman adduct derivatives were successfully sulfenylated to give the corresponding products in moderate to high yields. Control experiments and DFT calculations revealed deoxygenation of DMSO and nucleophilic addition of a sulfur intermediate as key steps in the entire mechanism.

Insertion reactions of diazo carbonyls to azlactones in basic conditions have been performed. The developed method allows the preparation of a wide range of oxazole derivatives in yields ranging from 74 to 98%. Different substituents on both azlactone rings and diazo carbonyls do not compromise the methodology, even those containing stereogenic centers. Isotopic labeling experiments revealed the mechanism may proceed through a rare diazo carbonyl activation by an ammonium salt derivative.

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