Identification of New Constituents of Quince Fruit Flavor (Cydonia oblo ga Mill. = C. vulgaris Pers.)

Article abstract of DOI:10.1021/jo00354a016

As a flavor of quince fruit, four new bicyclo<4.3.0>nonanes, 2,2,6,7-tetramethylbicyclo<4.3.0>nona-4,7,9(1)-triene (1), (+)-2,2,6,7-tetramethylbicyclo<4.3.0>nona-4,9(1)-dien-8-one (2), (-)-2,2,6,7-tetramethylbicyclo<4.3.0>nona-4,9(1)-dien-8-ol (3), and (-)-2,2,6,7-tetramethylbicyclo<4.3.0>nona-4,9(1)-diene-7,8-diol (4), have been identified.Racemic compounds 1-4 have been synthesized from 4-oxoisophorone by direct and regioselective reduction to 4-hydroxy-2,6,6-trimethyl-2-cyclohexen-1-one followed by ketal Claisen rearrangement. 3,4-Didehydro-β-ionol (5) has also bee n found to be one of the constituents of quince fruit oil.