Synthesis of five-membered 2-heteroaryl 2-heteroaromatic carboxylates and attempted cyclization to bisheteroaryl[2,3-<i>b</i>:3′,2′-<i>d</i>]pyran-2-one
作者:Chang Kiu Lee、Ji Sook Yu、Sun Hee Kim
DOI:10.1002/jhet.5570350409
日期:1998.7
2-Heteroaryl2-heteroaromaticcarboxylates were prepared by reactions of 2-heteroaromatic carbonyl chlorides and 2(5H)-furanone, 2(5H)-thiophenone, and 1-methyl-2(5H)-pyrrolone in triethylamine. The 1H nmr spectra of the esters showed that the electronic effect of both heteroaromatic rings did not cause any sizable shift from each other except for 1-methyl-2-pyrrolyl 1-methyl-2-pyrrolecarboxylate (5c)
通过使2-杂芳族羰基氯与2(5 H)-呋喃酮,2(5 H)-噻吩和1-甲基-2(5 H)-吡咯烷在三乙胺中反应制备2-杂芳基2-杂芳族羧酸酯。酯的1 H nmr光谱表明,除了1-甲基-2-吡咯基1-甲基-2-吡咯羧酸酯(5c)以外,两个杂芳族环的电子效应均不会引起任何可观的变化。尝试将酯环化成杂芳基稠合的吡喃-2-酮是不成功的。该结果可以用最稳定的酯构象来解释,其中两个杂原子沿酯基的C 0键为反。