“…The third cut was recrystallized twice from hexane to yield 4.23 g (12%) of 7-bromo-6-tertbutoxy-3-(hexafluoroisopropylidene)-2-thiabicyclo[2.2.1]heptane: mp 56-56.5°; nmr (CCI4) 1.15 [s, (CH3)3C], 2.25 (m, CH2), 3.42 (s, 1-H), 3.74 (4-H, broadened by F), 4.12 (m, 6-H), 4.25 38.14; H, 3.56; Br, 19.27. C. anti -7-Bromo-4,6-diphenyl-3-(hexafluoroisopropylidene)-2-thiabicyclo[2.2.1 ]hept-5-ene (19). 16 (4.12 g, 0.01 mol) was dissolved in 15 ml of dichloromethane, cooled, and stirred in ice, and 3.30 g (0.0105 mol) of tetramethylammonium tribromide40 was added in portions. Bromination followed by spontaneous dehydrobromination took place rapidly.…”