Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones.

Ping Qian,Jianlin Han,Yi Pan,Bingnan Du,Haibo Mei,Wei Jiao

doi:10.3762/bjoc.12.32

Abstract

An oxidative reaction for the synthesis of 4-alkyl-substituted dihydroisoquinolin-1(2H)-ones with N-allylbenzamide derivatives as starting materials has been developed. The radical alkylarylation reaction proceeds through a sequence of alkylation and intramolecular cyclization. The substituent on the C–C double bond was found to play a key role for the progress of the reaction to give the expected products with good chemical yields. Additionally, N-methacryloylbenzamides were also suitable substrates for the current reaction and provided the alkyl-substituted isoquinoline-1,3(2H,4H)-diones in good yield.

Highlights

The direct and selective functionalization of an unactivated sp3 C–H bond, which belongs to an effective strategic approach in green and sustainable chemistry, has attracted significant research attention [1,2,3,4]
The pioneering works were focused on the cross-dehydrogenative coupling (CDC) reactions of alkanes, which were reported by Li and other groups [11,12,13,14,15]
The substituent on the C–C double bond was found to play a key role for the formation of the desired products

Summary

Introduction

The direct and selective functionalization of an unactivated sp3 C–H bond, which belongs to an effective strategic approach in green and sustainable chemistry, has attracted significant research attention [1,2,3,4]. The reaction gave a complex mixture with 15% chemical yield of the expected product (Scheme 1c). When a methyl substituent was introduced onto the C–C double bond of the N-allylbenzamide substrate, the cyclization reaction proceeded smoothly (Scheme 1c). We found that the reactions did not happen or gave only a trace amount of the desired product with K2S2O8, AIBN, BPO and TBHP as oxidants (Table 1, entries 1, 3–5).

Results

Conclusion