Cyclic Oxime Esters as Deconstructive Bifunctional Reagents for Cyanoalkyl Esterification of 1,6-Enynes

Abstract

A concise copper catalysis strategy for the addition−cyclization of cyclic oxime esters across 1,6-enynes with high stereoselectivity to generate 1-indanones bearing an allcarbon quaternary center is reported. In this process, singleelectron reduction of cyclic oxime esters enables deconstructive carbon−carbon cleavage to provide a key cyanopropyl radical poised for the addition−cyclization. This reaction is redox-neutral, exhibits good functional group compatibility, and features 100% atomic utilization. This process driven by copper catalyst makes readily available cyclic oxime esters as bifunctional reagents to demonstrate convergent synthesis.

Exploiting the reactivities ofortho-alkynyl aryl ketones: opportunities in designing catalytic annulation reactions

“…To this end, 30 examples of functionalized 1-indanones 31 (Scheme 13) were synthesized with 45-72% yields and E/Z ratios between 2 : 1 and >19 : 1 by Jiang's group. 38 The variations in the three aryl rings of the two substrates were investigated and showed that both electron-rich (e.g., methyl, methoxy and tert-butyl) and electron-withdrawing (e.g., fluoro, chloro, bromo, trifluoromethyl, and cyano) groups were suitable for this reaction. Furthermore, the protocol could allow the direct deconstructive functionalizations of cyclobutanone oxime esters as bifunctional reagents, which led to high stereoselectivities in favor of the (E)-stereoisomer in most cases.…”

Visible-Light-Promoted Cyanoalkylation/Cyclization Cascade Reaction to Assemble Polyheterocycles in Continuous Flow

“…Recently, using cyclobutanone oximes and their derivatives as radical precursors has proven a versatile synthesis strategy for cyanoalkyl-containing molecules . In 2021, Jiang and co-authors reported a concise copper Heck-type cyanoalkylation from cyclic oxime esters via a process involving selective carbon–carbon cleavage to provide a key cyanopropyl radical used for cyanoalkyl esterification of 1,6-enynes . Alternatively, photocatalytic reactions provided a green synthetic tool for cyanoalkyl reactions starting from aryl alkynoates .…”

Photoinduced Etherification of Less-Strained Cycloketoxime Esters Enabled by C–C Bond Cleavage

“…Recently, cyclobutenone oxime esters − and substituted cyclopentanone oxime esters − were considered as good alkyl nitrile precursors for the construction of desired products. With our continuous interest in the C–C bond cleavage of cycloketoxime esters, − herein, we report a visible-light-induced redox-neutral etherification of ketoxime esters with the only requirement of photoredox catalyst, which is treated as an alternative route producing varied oxygenated ring-opening products from five-membered to eight-membered and linear cycloketoxime esters (Scheme d).…”