Bromination of decalin and its derivatives .9. High temperature bromination

Thermal and photobromination of decalin, 1, was studied, trans,cis,trans-2,5,7,9-tetrabromooctalin 2, was obtained as the major product along with smaller amounts of bromonaphthalene derivatives. The structures of the products were determined by H-1- and C-13-NMR data and single X-ray structural analysis. Bromination of the two decalin derivatives 9 and 10 results in the formation of single isomers 11 and 12, respectively. The three tetrabromides 2, 11, and 12 were shown by molecular mechanics calculations to be the most stable stereoisomer in each case. The formation of these tetrabromides under thermodynamic control is postulated.