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[摘要]：The chem. of endo-tricyclo[6.2.1.02.7]undec-9-en-11-ylidene (10), an archetypal foiled carbene, has been investigated. The intermol. reactions of 10 are most conveniently performed with oxadiazoline 6 because the corresponding diazirine can be obtained only in very low yield. Furthermore, the aziridinyl imine is difficult to decomp. and the tosylhydrazone sodium salt poorly sol. in common org. solvents. Photolysis of 6 in diethylamine leads merely to a redn. of the diazo group and regeneration of acetyl hydrazone 5, whereas thermolysis cleanly affords tertiary amine 12anti in 77% yield. Calcns. show that even stabilized-nucleophilic carbenes react with amines through an ylidic pathway and not by a concerted insertion into the N-H bond. Nevertheless, in the gas phase, norbornen-7-ylidene (13) is predicted to be stabilized by one mol. of NH3 more efficiently through a hydrogen bond than by ylide formation. |
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