ADDITION REACTIONS OF 4,4-DIMETHYLCYCLOHEXADIENYLIDENE

Diazo-4,4-dimethylcyclohexadiene (1) has been synthesized and decomposed under a variety of conditions. The resultant carbene, 4,4-dimethylcyclohexadienylidene (2), adds stereospecifically to trans-4-methyl-2-pentene and nearly so to cis-4-methyl-2-pentene. Adducts are also formed with dienes, acetylenes, and benzene. Remarkably, the product of addition to benzene is in the norcaradiene form. A comparison of relative rates of addition of 2 and cyclopentadienylidene (3) to olefins reveals differences which may indicate a quasi-aromatic structure for 3. © 1969, American Chemical Society. All rights reserved.