Generation and Reactions of 2-(1-Adamantyl)adamantene. Rearrangement to 3-(1-Adamantyl)-4-protoadamantylidene

Article abstract of DOI:10.1246/bcsj.69.2053

The S_N 1 methanolysis of (1-adamantyl)(3-noradamantyl)methyl heplafluorobutyrate at 100°C yielded (1-adamantyl)-(3-noradamantyl)methyl methyl ether (17), 2-(1-adamantyl)-1-methoxyadamantane (18), and 4-(1-adamantyl)-3-methoxyprotoadamantane (19) in a 2 : 65 : 33 ratio. The methanolysis of (1-adamantyl)(3-noradamantyl)diazomethane (7) at 0 °C also yielded 17, 18, and 19 in a 4 : 33 : 63 ratio. On the other hand, the photolysis of 7 in 99 : 1 (v/v) hexane-methanol gave 17,18, 2-(1-adamantyl)-2-methoxyadamantane (25), and 2-(1-adamantyl)-2,4-didehydroadamantane (20) in a 30 : 9 : 36 : 25 ratio. Presence of triethylamine decreased the yields of ethers 17, 18, and 25, and increased the yield of 20 to 46%. The formation of a considerable amount of 17 and the absence of 19 in the photolysis products indicate the generation of (1-adamantyl)(3-noradamantyl)methylidene (8). The formation of 25 and 20 suggests that the generated carbene 8 rearranges to 2-(1-adamantyl)adamantene (3b) and then gives 3-(1-adamantyl)-4-protoadamantylildene by the subsequent retro-insertion. An attempt to isolate 3b in the photolysis of 7 in cyclohexane failed, and the sole isolated product was 20.