Pyrolysis of Tetracyclo[5.3.0.02,10.03,6]decene-8. a (2′-Vinylcyclopropyl) cyclobutane Rearrangement

Pyrolysis of tetracyclo[5.3.0.02,10.03,6]decene-8 (V) (believed to be 3,6-endo) in the vapor phase (~100 Torr) in a static system at 250° gave three isomeric products in the ratio of 4:2:1. The first of these was tricyclo-[5.2.1.04,10]deca-2,5-diene (VI). The second was found to be the exo stereoisomer (VIII) of the starting material. The third isomer was not further identified. In a fast-flow system at 550° at a pressure of <1 Torr, the products were VI and 1,2-dihydronaphthalene. From kinetic studies and by deuterium labeling, the formation of VI was shown to involve a shift of the C3C4 bond in V to the C8 position. Thus, this reaction can be regarded as the rearrangement of a (2′-vinylcyclopropyl)cyclobutane system to a 1,4-cyclononadiene. © 1970, American Chemical Society. All rights reserved.