β-(2,4,6-Cycloheptatrien-1-yl)ethylcarbene. The Synthesis of 9-Substituted Bicyclo[4.2.1]nona-2,4,7-trienes and 9-Substituted Barbaralanes

Abstract

Abstract The thermal decomposition of sodium salt of (2,4,6-cycloheptatrien-1-yl)acetaldehydes tosylhydrazone (4, 6, and 8) afforded 9-substituted bicyclo[4.2.1]nona-2,4,7-triene (9, 11, and 14) and 9-substituted barbaralane (10, 12, and 15). In the case of 8, products containing two nitrogen atoms (17 and 18) were isolated. The structure and the photochemical reaction of 17 provided strong support for the intermediacy of the tetracyclo[4.3.0.02,9.05,7]-nona-3-ene (37) derivative for the formation of the bicyclo[4.2.1]nona-2,4,7-triene derivatives. The difference in energy surface between C9H10 and C10H10 hydrocarbons was discussed.