STRUCTURE AND SYNTHESIS OF NOVEL C-12 TERPENOIDS FROM QUINCE FRUIT (CYDONIA-OBLONGA MILL)

The structure and synthesis of novel irregular C-12 terpenoids isolated from quince fruit (Cydonia oblonga MILL.) are described: quince oxepine (= (E)-2,3,6,7-tetrahydro-4-methyl-2-(3-methylbuta-1,3-dinyl)oxepine; 3) and the quince oxepanes as a 1:1 mixture of cis- and trans-isomers (= cis- and trans-(E)-4-methyl-2-(3-methylbuta-1,3-dienyl)oxepane; 4 and 5, resp.). The absolute configurations of the natural compounds have not been determined due to the minute amounts available, but both relative and absolute configurations of synthetic 4 and 5 were established by chemical correlation with (R)-pulegone.