Conversion of (Z)-1,4-dihydroxyalk-2-enes into 2,5-dihydrofurans and of alkane-1,4-diols into tetrahydrofurans via acid-catalysed cyclisation of the monoisoureas formed by their copper(i)-mediated reactions with dicyclohexylcarbodiimideElectronic supplementary information (ESI) available. Experimental data for compounds 14a–f, 15a–f, 7a–f, 22a–g, 21a–e and 2b–e: See http://www.rsc.org/suppdata/p1/b2/b203389p/
作者:Michael G. Duffy、David H. Grayson
DOI:10.1039/b203389p
日期:2002.6.27
(Z)-1,4-Dihydroxyalk-2-enes react with dicyclohexylcarbodiimide in the presence of catalytic amounts of copper(I) chloride to give O-alkyl monoisoureas which cyclise to give 2-substituted-2,5-dihydrofurans and dicyclohexylurea when they are treated with trifluoroacetic acid. Alkane-1,4-diols likewise give O-alkyl monoisoureas which cyclise to yield tetrahydrofurans.
(Z)-1,4-二羟基烯烃与N,N-二环己基碳二亚胺在催化量的氯化铜(I)存在下反应,生成O-烷基单异氰酸酯,后者经三氟甲酸处理后环化生成2-取代的2,5-二氢呋喃和N,N-二环己基脲。同理,烷烃-1,4-二醇也生成O-烷基单异氰酸酯,环化后得到四氢呋喃。