Visible‐light‐mediated Synthesis of Bromo‐containing Azaspirotrienediones from N‐phenylpropynamides

Abstract

A visible‐light‐mediated reaction of N‐phenylpropynamides with diethyl 2,2‐dibromomalonate for the synthesis of bromo‐substituted azaspirotrienediones has been developed. This method allows the formation of C−Br, C−C and C=O bonds in one pot via a cascade radical addition/ipso‐cyclization/oxidation process. A possible radical mechanism involving single electron transfer and energy transfer processes is proposed based on control experiments, cyclic voltammetry determination and Stern‐Volmer quenching experiments.

Visible-light induced dearomatization reactions

“…They expanded this strategy for the synthesis of bromo-containing azaspirotrienediones 47, using the diethyl 2,2-dibromomalonate 46 as the bromine radical precursor. 49 The practical application of photocatalytic dearomatization was illustrated by the Inuki and Ohno group in the total synthesis of Zephycarinatines where the key step involved a stereoselective reductive radical ipso-cyclization enabled by visible-light-mediated photocatalysis in 2020 (Scheme 16). 50 At the beginning, only a trace amount of the desired product 49 was obtained.…”

Electrophilic Sulfenylation/Cyclization of N‐Aryl and N‐Benzyl Propynamides: Synthesis of Sulfenyl Quinolinones and 3H‐Benzo[c]azepin‐3‐ones

“…The authors have cited additional references within the Supporting Information. [22][23][24][25][26][27][28][29][30][31]…”

Cerium(IV)‐Mediated Carbon‐Carbon Bond Formation for the Synthesis of Spirodienone Lactams

“…Moreover, it has been reported in the literature that the formation of spirocyclic compounds may occur from electron-poor alkynes for instance through the addition of a radical leading to the conclusion that ynamidephosphonates such as 34 may be of interest in the synthesis of spirocyclic compounds. [35][36][37][38][39][40][41] With the goal to prepare the spirodienone lactam 16 b (EWG = Ts) we next explored the reactivity of the ynamidophosphonates 34 [34] towards the oxidation with CAN in CH 3 CN. In that case, the oxidation of 34 led to the formation of the three products 35-37 resulting from the easier oxidation of the alkyne moiety in comparison to the PMB ring.…”