Acetyl cedrene and its follower. An Isotopic, NMR and MS Structure elucidation and deuteriation study

摘要

Acetylation of cedarwood oil (Virginia) leads besides acetyl cedrene also to a minor product, 1,7,7-trimethyl-2,3-(3',4'-dimethylbenzo)bicyclo[3.2.1]octane (follower). This product is identified by 2D NMR. Acetylation of cedarwood oil with ~(13)C-1 labeled acetic acid anhydride leads to a product labeled at the aromatic carbon C-3'. From the ~(13)C-labeled compound ~(13)C-~(13)C coupling constants could be measured. Acetyl cedrene is conveniently deuteriated by an acid-catalysed exchange reaction using trifluoroacetic anhydride and D_2O. The product is found to be deuteriated both at the acetyl group and at the methyl group at the double bond (carbon 6). The reaction condition during deuteriation of cedrol leads to the elimination of the hydroxyl group at C-6 with the formation of a-cedrene deuteriated at H-5 and the methyl group at C-6. Deuteriation of the follower leads to deuterium exchange at the aromatic carbons C-5' and C-6'.