D. Farcasiu, J. Slutsky, P. Schleyer
1977
Citations
0
Influential Citations
6
Citations
Journal
Tetrahedron
Abstract
Abstract The minor product, 4-protoadamantene ( 5 ), from the gas phase pyrolysis of 2-adamantyl mesylate ( 3 ) was shown by labelling experiments not to arise from the major product, 2,4-dehydroadamantane ( 4 ), but rather by a concerted process (homo-retroene reaction). In the formation of 4 , 1,3-elimination is favored by at least a 92:8 margin over a competitive route involving α-elimination to a carbene and then C-H insertion. Equatorial and axial 2-noradamantyl mesylates pyrolyze to give predominantly 4 -brendene ( 11 ) and triaxane ( 12 ), respectively, as required by concerted 1,3-eliminations, and not by an ion pair mechanism. The cross-over product appears in each case to result from the epimerizarion of the starting material by a wall-catalyzed process. In agreement with the results of the noradamantyl substrates, pyrolysis of 3-diamantyl mesylate ( 16 ) gave results which suggest that product stability helps to determine the course of the reaction. The products with the least amount of strain were obtained, namely 3,5-dehydrodiamantane ( 17 ) and pentacyclo[8.3.1.0 2,8 .0 4,13 .0 7,12 ]tetradec-5-ene ( 19 , protodiamantene). The ease of separation of the cyclopropanic and olefinic products makes these reactions synthetically useful.