Sodium Carbonate → 3a,6-Epoxy-7-isopropyl-1,4-dimethyl-2,3,3a,4,5,6,7,8-octahydroazulene

Participants

Reaction Steps

To a solution, cooled to -40°, of 3.3 g of 2-(2-formyl-3-methylbutyl)-3-isopropenyl-1-methyl-1-cyclopentene in 225 ml of nitromethane were added 45 ml of a 0.5-M solution of tin tetrachloride in nitromethane. The reaction mixture became intensely yellow in colour and an initially resulting precipitate dissolved again. The mixture was treated immediately with excess 2-N sodium carbonate solution and extracted with ether. After washing, the ethereal phase was dried in a conventional manner and the solvent was removed. Distillation under a high vacuum yielded 2.6 g of crude 3a,6-epoxy-7-isopropyl-1,4-dimethyl-2,3,3a,4,5,6,7,8-octahydroazulene in the form of a colourless oil which could be separated by chromatography on 40 times the amount of Florisil (magnesium silicate gel) with hexane/ether (19:1) into two pairs of epimers (A and B). Epimer A: b.p.0.01 ca 75°; IR(film): νmax = 1465/40, 1380, 1345, 1245, 1162, 1125, 1108, 1080, 1050, 995, 965, 945, 910, 880 cm-1. The odour is camphorous, woody. Epimer B: b.p.0.01 ca 80° IR(film): νmax = 1465/34, 1380, 1340, 1295, 1245, 1200/1195, 1170, 1145, 1110, 1060, 1030, 1000, 990, 950, 925, 910, 878 cm-1. The odour is camphorous, dull.

Provenance & Evidence