Palladium-Catalyzed C–H Alkenylation of Arenes Using Thioethers as Directing Groups

Abstract

Thioethers have been proven to be reliable directing groups for palladium catalyzed alkenylation of arenes via C-H activation. Mechanistic investigation reveals that the C-H cleavage of arenes is the turnover-limiting step, and an acetate-bridged dinuclear cyclopalladation intermediate is involved. The alkenylated thioethers can be easily removed and transformed into a variety of useful groups.

Unexpected Synthesis of 2,3,5,6‐Tetrahydro‐1H‐pyrrolo[3,4‐c]pyridine‐1,3,6‐triones by a Double Michael Addition/CS2 Extrusion/Double Cyclization Sequence

“…To the best of our knowledge, just one example of ringopening/ring-closing process of the rhodanine core is reported in the literature. [12] Differently from this, our sequence occurs with the loss of a molecule of carbon disulfide, which activates the substituted nitrogen atom of the rhodanine as nucleophile in the first cyclization event.…”

Conformationally Restricted Triarylmethanes: Synthesis, Photophysical Studies, and Applications

“…[68] Another method, involving copper ion mediated rhodamine spirolactam ring opening was developed by Xiao and co-workers (Scheme 39). [69] Conversion of the regioisomeric mixtures to their corresponding hydrazide in isomerically pure form was achieved by treatment with hydrazine hydrate followed by column purification of the respective formed hydrazide. Further, a copper(II) chloride mediated hydrolysis then yielded the 5th regioisomer in moderate yield (approx.…”

Synthesis of Benzopyrans by Enolate‐Directed Rhodium‐Catalyzed Oxidative C−H Alkenylation of 1,3‐Dicarbonyl Compounds

“…[10] However,several drawbacks, including low selectivity,has limited the practicality of this transformation. This drawback is miti-gated by chelation-assisted CÀHf unctionalization strategies in which ad iverse range of directing groups including ureas, [11] thioethers, [12] anilides, [13] amides, [14] hydrazones, [15] 1,2,3-triazoles, [16] carboxylic acids, [17] and carbamates, [18] have been reported.…”