Visible-Light-Mediated Synthesis of Rutaecarpine Alkaloids through C–N Cross-Coupling Reaction

Abstract

A visible-light-initiated cross-dehydrogenative-coupling amination is described, featuring metal- and photocatalyst-free, at room temperature, and using air as an oxidant. The reaction provides a facile approach for the synthesis of rutaecarpine and its derivatives. The substrates with electron-withdrawing groups give higher yields than those with electron-donating groups, but the substituent position has a negligible influence on the yield. Using binaphthyl-diyl hydrogen phosphate and dibenzyl phosphate as catalysts both deliver satisfying yields.This straight-forward light-driven strategy might be applicable to the synthesis of quinazolinone derivatives.

Synthesis of bioactive evodiamine and rutaecarpine analogues under ball milling conditions

“…28 mp: 300–301 °C; lit. 39 mp: 294–296 °C). 1 H NMR (400 MHz, CDCl 3 ) δ 9.11 (brs, 1H), 8.27 (brs, 1H), 7.67–7.61 (m, 2H), 7.59 (d, J = 8.4 Hz, 1H), 7.45 (d, J = 8.4 Hz, 1H), 7.36 (t, J = 7.6 Hz, 1H), 7.20 (t, J = 7.6 Hz, 1H), 4.58 (t, J = 6.9 Hz, 2H), 3.24 (t, J = 6.9 Hz, 2H); 1 H NMR (400 MHz, DMSO- d6 ) δ 11.88 (brs, 1H), 8.09 (brs, 1H), 7.83 (m, 1H), 7.67 (m, 2H), 7.49 (m, 1H), 7.28 (m, 1H), 7.10 (m, 1H), 4.45 (m, 2H), 3.19 (m, 2H); 13 C NMR (100 MHz, CDCl 3 ) δ 160.8, 146.3, 145.2, 138.5, 134.9, 132.0, 128.4, 127.1, 126.8, 126.0, 125.8, 122.3, 121.0, 120.3, 118.8, 112.2, 41.5, 19.8; 13 C NMR (100 MHz, DMSO- d6 ) δ 159.6, 146.1, 145.7, 138.7, 134.5, 130.0, 128.7, 126.8, 125.5, 124.9, 124.8, 121.8, 120.0, 119.8, 118.3, 1125, 41.0, 18.8; the NMR data are in accordance with the literature data.…”