Synlett 2018; 29(05): 617-620
DOI: 10.1055/s-0036-1591522
letter
© Georg Thieme Verlag Stuttgart · New York

Metal-Free Cascade Methylation/Cyclization of N-Alkyl-N-methacryloylbenzamides with Dicumyl Peroxide

Yan-Ning Niu*
a   Department of Teaching and Research, Nanjing Forestry University, Huaian, Jiangsu, 223003, P. R. of China.   Email: zjsnyn@163.com
,
Xiao-Feng Xia*
b   Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. of China.   Email: xiaxf@jiangnan.edu.cn
,
Yuan Yuan
a   Department of Teaching and Research, Nanjing Forestry University, Huaian, Jiangsu, 223003, P. R. of China.   Email: zjsnyn@163.com
› Author Affiliations
We thank the National Science Foundation of China NSF 21402066, the Natural Science Foundation of Jiangsu Province (BK20140139), the science and technology plan project of Huaian (HAGZ201614), and MOE&SAFEA for the 111 project (B13025) for financial support.
Further Information

Publication History

Received: 14 October 2017

Accepted after revision: 18 November 2017

Publication Date:
20 December 2017 (online)


Abstract

A metal-free radical cascade methylation/cyclization of a wide range of N-alkyl-N-methacryloylbenzamides by using dicumyl peroxide as the methylating reagent provides a convenient access to a series of methylated isoquinoline-1,3-diones in moderate yields.

Supporting Information

 
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  • 9 4-Ethyl-2,4-dimethylisoquinoline-1,3(2H,4H)-dione (3a); Typical Procedure DCP (0.6 mmol) was added to a stirred solution of N-methacryloyl-N-methylbenzamide (1a; 0.2 mmol) in PhCl (1.0 mL) in a test tube. The tube was sealed, and the mixture was stirred at 120 °C for 17 h. H2O (5 mL) was added to quench the reaction, and the mixture was extracted with EtOAc (3 × 10 mL). The organic layers were combined, washed with sat. aq NaCl (2 × 10 mL), dried (Na2SO4), and concentrated. The residue was purified by column chromatography [silica gel, hexanes–EtOAc (8:1)] to give a colorless oil; yield; 26 mg (60%).IR (KBr): 3066, 2966, 2934, 2876, 1714, 1667, 1606, 1463, 1416, 1361, 764 cm–1. 1H NMR (400 MHz, CDCl3): δ = 8.26–8.28 (m, 1 H), 7.64–7.68 (m, 1 H), 7.42–7.48 (m, 2 H), 3.41 (s, 3 H), 2.29–2.36 (m, 1 H), 1.86–1.92 (m, 1 H), 1.64 (s, 3 H), 0.56 (t, J = 8.0 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 176.6, 164.5, 143.4, 133.9, 128.7, 127.2, 125.2, 48.3, 36.6, 28.5, 27.0, 9.4. Anal. Calcd For C13H15NO2: C, 71.87; H, 6.96; N, 6.45. Found: C, 71.68; H, 7.01; N, 6.39.