SYNTHESIS OF ISOCOUMARINS FROM O-IODOBENZOIC ACID AND TERMINAL ACETYLENES MEDIATED BY PALLADIUM COMPLEXES AND ZINC-CHLORIDE

被引：154

作者：

LIAO, HY ^{[1
]}

CHENG, CH ^{[1
]}

机构：

[1] NATL TSING HUA UNIV, DEPT CHEM, HSINCHU 300, TAIWAN

来源：

JOURNAL OF ORGANIC CHEMISTRY | 1995年 / 60卷 / 12期

关键词：

D O I：

10.1021/jo00117a023

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

o-Iodobenzoic acid (1) reacts with various terminal acetylenes (HC=CR) in the presence of Pd(PPh(3))(4), Et(3)N, and ZnCl2 in DMF to give the corresponding 3-substituted isocoumarins (C6H4COOC(R)CH: R = n-C4H9 (2a); n-C3H7 (3a); CH2OCH3 (4a); C(CH3)(2)OH (5a); CH2OH (6a); C6H5 (7a);p-CH3C6H4 (8a); 1-cyclohexenyl (9a); o-NH2C6H4 (10a)) in fair to excellent yields, In some of these catalytic reactions, substituted isocoumarin b (C6H4COOC(R)C(C=CR)) and alkylidenephthalide c were isolated in a few percent yields, Under similar conditions, treatment of 1 with a trimethylsilyl 1,3-diyne 12 led to the formation of products 3-(2-indolyl)isocoumarin (13) and an indolylphthalide 14 in a 95:5 ratio. The reaction of o-1-pentynylbenzoic acid with ZnCl2 and Et(3)N gave 3a as the sole product indicating that ZnCl2 is likely responsible for the selective formation of the six-membered isocoumarin ring, Based on this observation and the known palladium chemistry, a mechanism involving the participation of palladium complexes in the alkynylation of 1 and zinc chloride in the heteroannulation of the reaction intermediate o-1-alkynylbenzoate is proposed for the present catalytic reactions.

引用

页码：3711 / 3716

页数：6

共 34 条

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