Copper-Catalyzed Regioselective 1,4-Selenosulfonylation of 1,3-Enynes to Access Cyanoalkylsulfonylated Allenes

Abstract

By employing CuOAc as the catalyst, we realize a four-component reaction of 1,3-enynes, diselenides, DABCO·(SO2)2, and cycloketone oxime esters, providing facile access to diverse cyanoalkylsulfonylated allenyl selenides in moderate to good yields. This reaction features high functional group tolerance and a broad substrate scope, enabling the regioselective, sequential formation of C–SO2 and C–Se bonds under mild reaction conditions. Moreover, the utility of this methodology is further illustrated through the late-stage functionalization of drug-based molecules.

Ni and Fe catalyzed cascade radical reactions of oxime esters with diselenides

“…Based on the above findings and relevant research works previously reported, 16,27,48,49 a plausible reaction mechanism for the selenylation of oxime esters was proposed (Scheme 3). Initially, γ,δ-unsaturated oxime ester 1a undergoes an N-O bond cleavage via a single-electron transfer (SET) process aided by the Ni or Fe catalyst to yield iminyl radical A.…”

“…The catalyst is likely regenerated with the assistance of the added base. 48 A similar reaction mechanism can be envisaged for the ring-opening of cyclic oxime esters, via a carbon-centered cyanoalkyl radical.…”

“…The scope of this reaction was further extended to disulfides and ditellurides, demonstrating the applicability in organic synthesis. 45 Furthermore, recent studies by Sun 46,47 and Wu 48 demonstrate the utility of diselenides as free radical acceptors.…”

Radical transformations for allene synthesis

“…Shortly after Ma's work, Wu, He, and coworkers developed a fourcomponent synthesis of allenes taking advantages of the sulfonylgroup insertion process (Scheme 12). 28 Under the optimal copper catalysis, the reactions with 1,3-enynes, diselenides, DABCO•(SO 2 ) 2 , and cyclobutanone oxime esters provided a facile access to many kind of cyanoalkylsulfonylated allenyl selenides 15 in moderate to good yields. The key step lies in sulfonyl-group insertion before the Please do not adjust margins Please do not adjust margins regioselective addition of the alkyl group onto the 1,3-enyne.…”

N-Heterocyclic Carbene-Catalyzed 1,4-Alkylacylation of 1,3-Enynes

“…Upon the initial radical addition, the resulting intermediate could exist as a propargyl/allenyl resonance radical. It was recently established that the allenyl radical reacted readily with organometallics, especially Cu ,,− and Ni, and underwent subsequent coupling reactions (Scheme B). In 2018, Liu and co-workers reported a copper-catalyzed trifluoromethylcyanation reaction .…”