Benzyne, cyclohexyne, and 3-azacyclohexyne have been obtained by flash vacuum pyrolysis of phthalic anhydride, 4-cyclopentylidene-3-methylisoxazol-5(4H)-one (34), and 3-methyl-4-(2-pyrrolidinylidene)isoxazol-5(4H)-one (37), respectively, isolated at 77 K and observed by IR spectroscopy. Trapping and fragmentation reactions are described, and the implications for the mechanism of benzyne formation from
1,5-Cyclooctadiyne 1 was isolated in 2 percent yield from polymerized butatriene 5. Other oligomers of 5 were detected in the reaction mixture by combined GLC./MS. analysis but have not been identified. Diels-Alder adducts of 1 with two equivalents of 1,3-butadiene and of 2,3-dimethyl-1,3-butadiene have been prepared. In the presence of strong base 1 isomerized to cyclooctatetraene. 5 was reformed
1-Bromobicyclo[1.1.0]butanes and strong bases: products and mechanism
作者:Axel Düker、Günter Szeimies
DOI:10.1016/s0040-4039(00)89189-3
日期:1985.1
Treatment of the bromobicyclo[1.1.0]butanes (=4)(=a) - (=c) with LDA led to the formation of the 1,2,3-butatrienes (=6) which were isomerized by excess base to the alkynes (=8). Reaction of [1-12-C](=4)(=c) with LDA afforded [3-12-C](=8)(=d), indicating that bicyclo[1.1.0]but-1(3)-ene (=5) was not an intermediate.
Reaction of potassium trithiocarbonate with 1,4-dichloro-, 1,4-bis(tosyloxy)- or 1,4-dibromo-2-butyne (1a-c) affords 4-vinylidene-1,3-dithiolane-2-thione (2) in excellent yields. The trithiocarbonate 2 is desulfurized with 1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine (3) to give butatriene (4) under very mild conditions
Azo-coupling and reduction of cyclopropanediazonium ions in the reactions with polyhydroxyarenes and aminophenols
作者:E. V. Shulishov、I. P. Klimenko、V. A. Korolev、I. V. Kostyuchenko、G. P. Okonnishnikova、Yu. V. Tomilov
DOI:10.1007/s11172-008-0225-2
日期:2008.8
A reaction of cyclopropanediazonium ion, generated by decomposition of N-cyclopropyl-N-nitrosourea upon treatment with potassium or cesium carbonates, with various poly-hydroxyarenes and aminophenols has been studied. The reaction of azo-coupling proceeds with phloroglucinol, resorcinol, 3-methoxy- and 3-aminophenol giving rise to mono-, bis-, and tris(cyclopropylazo)arenes as the major products. Oxidizable phenols such as hydro-quinone, 2-methoxy-, 4-amino-, and 2-aminophenol give products of radical transformations with participation of cyclopropyl radical.