chromatography of 1 2 g portions through a 2 5 u00d7 100 cm altex column packed with 40 63 u03bc silica gel eluting with hexane ethyl acetate 7 1 the more polar alphas isomer was resubmitted to the lithium bromide acetone equilibration separation sequence described above three more times to give a total yield of 7 1 g 63 of 3as 3a alpha 3 r r 7beta 7a beta 7 acetyloxy alpha bromo 3a 4 5 6 7 7a hexahydro gamma 3a dimethyl 1h indene 3 butanoic acid methyl ester the analytical sample was recrystallized from hexane ether mp 62 u00b0 c u03b1 d 25 41 14 u00b0 c 1 0063 chcl 3 calcd for c 18 h 27 bro 4 c 55 82 h 7 03 br 20 63 found c 56 06 h 7 10 br 20 44 in a separate experiment the analytical sample of the other isomer 3as 3a alpha 3 r s 7 beta 7a beta 7 acetyloxy alpha bromo 3a 4 5 6 7 7a hexahydro gamma 3a dimethyl 1h indene 3 butanoic acid methyl ester was obtained as an oil by eliminating the lithium bromide acetone equilibration step u03b1 d 25 40 91 u00b0 c 0 9925 chcl 3 calculated for c 18 h 27 bro 4 c 55 82 h 7 03 br 20 63 found c 55 50 h 6 92 br 20 65 to a solution of 92 2 ml of 20 diisobutylaluminum hydride in hexane and 90 ml.