Patent ID: 6201155
Filing Date: 2001-03-13
Classification: C07C,C07D

Abstract:
A process for the manufacture of a symmetrical, terminally ring-substituted polyenes of formula I: ##STR18##whereinR.sup.1 is hydrogen or hydroxy;m is 0 or 1; andn is 0, 1, or 2,the process comprising(a) reacting a polyene di(O,O-dialkyl acetal) of formula II: ##STR19##whereinR.sup.2 is C.sub.1-6 -alkyl andn is 0, 1, or 2,with a cyclic dienol ether of formula III: ##STR20##whereinR.sup.3 is hydrogen;R.sup.4 is C.sub.1-4 -alkoxy; orR.sup.3 and R.sup.4 together form an optionally substituted methylenedioxy group, --O--C(R.sup.5)(R.sup.6)--O--, wherein R.sup.5 and R.sup.6 are each independently hydrogen, C.sub.1-4 -alkyl, or phenyl, andm is 0 or 1;in the presence of a Lewis or Bronsted acid,(b) hydrolyzing the reaction product under acidic conditions; and(c) cleaving off the alkanol R.sup.2 OH from the thus-obtained compound of formula IV: ##STR21##whereinR.sup.1 is hydrogen or hydroxy depending on whether R.sup.3 and R.sup.4 in formula III are hydrogen and C.sub.1-4 -alkoxy, respectively, or R.sup.3 and R.sup.4 together form the optionally substituted methylenedioxy group, andR.sup.2, m and n are as previously defined in this claim,under basic or acidic conditions.