One-shot access to α,β-difunctionalized azepenes and dehydropiperidines by reductive cross-coupling of α-selenonyl-β-selenyl enamides with organic bromides

Abstract

The synthesis of α- and α,β-functionalized azepenes and dehydropiperidines from readily prepared α-selenonyl eneformamides or enecarbamates has been achieved through Fe-catalyzed α-substitutive deselenonation, β-regioselective lithiation/trapping, and Co-catalyzed reductive cross-coupling protocols.

Modern Synthetic Strategies with Organoselenium Reagents: A Focus on Vinyl Selenones

“…The electron-withdrawing nature of the selenonyl group also facilitated the β-functionalization of the aza-heterocycles by lithiation and trapping with selenium electrophiles (route b). The aza-heterocycles were then vicinally difunctionalized with different carbon partners (route c–d), taking advantage of the diverse reactivity of the two selenylated functional groups [ 62 ]. In fact, the coupling between the β-selenyl group and the aryl bromide required warming to 40 °C.…”

Regiocontrolled synthesis of (hetero)aryl and alkenyl dehydropyrrolidines, dehydropiperidines and azepenes by Ru-catalyzed, heteroatom-directed α-C–H activation/cross-coupling of cyclic enamides with boronic acids

“…30 Continuing our quest for expedient-, practical-and complementary-methods for accessing functionalized Department of Chemistry, Central Washington University, Ellensburg, WA 98926, USA. E-mail: TimothyB@cwu.edu azaheterocycles, 24,25,[33][34][35][36][37][38][39][40][41][42][43] and the cognizant of the inherently high reactivity of unfunctionalized cyclic enamides such as V (relative to the corresponding saturated cyclic amine), it was surmised that regioselective sp 2 α-C-H functionalization/crosscoupling of the latter with boronic acids, under ruthenium catalysis, offered an attractive approach (Fig. 2E).…”