Journal of the Chemical Society. Perkin transactions I p. 2626 - 2630 (1980)
Update date:2022-08-04
Topics:
Bondavalli, Francesco
Schenone, Pietro
Ranise, Angelo
Lanteri, Silvia
An efficient transposition of carbonyl group R1-CO-CH2-R2 -> R1-CH2-CO-R2 in the 1,3,3-trimethyl-2-oxabicyclo<2.2.2>octane system was carried out via hydroboration-oxidation of 6-dialkylamino-1,3,3-trimethyl-2-oxabicyclo<2.2.2>oct-5-enes (3a-c), which gave regio- and stereo-specifically 6-cis-dialkylamino-1,3,3-trimethyl-2-oxabicyclo<2.2.2>octan-5-trans-ols (4a-c) in high yield.Cope reaction on the N-oxide (5b) obtained from the amino-alcohol (4b) with hydrogen peroxide led to 1,3,3-trimethyl-2-oxabicyclo<2.2.2>octan-5-one (6), the other possible isomer of the long-known 1,3,3-trimethyl-2-oxabicyclo<2.2.2>octan-6-one (1b).The ketone (6) was also obtained from 1,3,3-trimethyl-2-oxabicyclo<2.2.2>oct-5-ene (2) via its trans-epoxide (11), lithium aluminium hydride reduction at 160-165 deg C of which gave stereo- and regio-specifically 1,3,3-trimethyl-2-oxabicyclo<2.2.2>octan-5-trans-ol (9b).Chromic acid oxidation of (9b) and (4a-c) under various conditions gave the ketone (6) and the amino-ketones (7a-c), respectively.Lithium aluminium hydride reduction of (6) and (7a-c) afforded stereospecifically the cis-alcohol (9a) and 6-cis-dialkylamino-1,3,3-trimethyl-2-oxabicyclo<2.2.2>octan-5-cis-ols (8a-c), respetively.Hydroboration-oxidation of the alkene (2) was not regiospecific, giving a 3:1 mixture of the trans-alcohols (9b) and (10b), respectively.
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Doi:10.1021/ja00398a027
(1981)Doi:10.1016/S0040-4039(01)83023-9
(1981)Doi:10.1016/0040-4039(80)80219-X
(1980)Doi:10.1021/ja00394a040
(1981)Doi:10.1016/S0040-4039(99)00299-3
(1999)Doi:10.1007/BF00571045
(1980)
