| abstract |
This invention relates to a process for preparing the compounds of lignan series in a selective manner in terms of the positions, and to intermediates thereof. This invention provides a process for preparing compounds of the formula (I): (See formula I) which is characterized by that a lactone compound of the formula (II): (See formula II) is reacted with an unsaturated ketone represented by the formula (III): (See formula III) and the resulting compound is subjected to dehydration in which, R1 is alkyl, cycloalkyl, cycloalkyl (lower alkyl), or aralkyl; R2 and R3 each is lower alkyl or R2 and R3 are combined together to form an alkylenedioxy; R4 is lower alkoxy or hydrogen; R5 and R6 each is lower alkyl; and R7 is lower alkyl. The invention also provides the compounds of the formulas (II) and (III). |