反应详情

The compounds of formula I in which R is hydrogen can be prepared by reacting a 3,5 -dialkanoyloxybenzaldehyde (III) with 1,2-ethanedithiol to produce a 1,3-dialkanoyloxy-5-(1,3-dithiolan-2-yl)benzene (IV), hydrolyzing the 1,3-dialkanoyloxy ester to produce 5-(1,3-dithiolan-2-yl)resorcinol (V), reacting compound V with p-mentha-2,8-dien-1-ol to produce 3-(1,3-dithiolan-2-yl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol (VI) which is then subjected to oxidative cleavage conditions to produce a compound of formula I named 3-formyl-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-1-ol. This process can be represented as follows: ##STR9## wherein R5 represents a lower alkanoyl group, such as the acetyl, propionyl and butyryl groups.