engleski

4-Homoadamantyl cation. II. Mechanistic studies on Lewis acid catalyzed conversion of homoadamantene to 2-methyladamantane by carbon-13 labeling techniques. Convenient synthesis of 4-homoadamantanone-5-13C and homoadamantene-4-13C

The Lewis acid catalyzed conversion of homoadamantene-4-13C in CS:! yielded 20% of 2-methyladamantane with the majority of the label equally distributed between the CY position and the methyl group, indicating that only the olefinic carbons were involved in this rearrangement. The mechanism probably involves protonation of the olefinic bond by AlXpH20 to form the classical 4-homoadamantyl cation. This cation appears to rearrange rapidly to an unsymmetrically bridged 2-adamantylcarbinyl cation which yields 2-methyladamantane by hydride abstraction. The degenerate homoadamantyl rearrangement is retarded in such a low polar solvent as CS:! presumably by intimate ion pairing. 4-Hom0adamantanone-5-~w~aCs prepared in 46% overall yield by addition of (CH3)3Si13CN to adamantanone followed by LiAlHr reduction of the a-trimethylsilyloxy nitrile and Demjanow- Tiffeneau ring enlargement of the resulting u-aminomethyl alcohol [[CH&Sil3CN was obtained in 88% yield from (CH3)3SiCl and Ag13CN]. This synthetic procedure appears to be a convenient general method for the preparation of "C-labeled ketones and their derivatives.

4-Homoadamantyl cation, Lewis acid, 4-homoadamantanone-5-13C, homoadamantene-4-13C

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