Patent ID: 6103940
Filing Date: 2000-08-15
Classification: C07C,C07D,C07F

Abstract:
A process for preparing (3R,3'R)-zeaxanthin of the formula I ##STR30## which comprises A. (4R)-4-hydroxy-2,2,6-trimethylcyclohexanone of the formula II ##STR31## being reacted with dichloromethyl lithium in an inert solvent at from -120 to -40.degree. C.,B. the novel (4R,6R)-1-formyl-2,2,6-trimethyl-7-oxabicyclo[2.2.1]heptane of the formula IV ##STR32## which is obtained on warming the reaction mixture to 20 to 60.degree. C., being reacted either in isolated form, or else directly in the form of the resulting reaction mixture with acetone or a dialkyl 2-oxopropylphosphonate,C. the resulting novel (4R,6R)-1-(3-oxo-1-butenyl)-2,2,6-trimethyl-7-oxabicyclo[2.2.1]heptane of the formula V ##STR33## being converted by vinylation or ethynylation and subsequent partial hydrogenation into the novel (4R,6R)-1-(3-hydroxy-3-methyl-1,4-pentadienyl)-2,2,6-trimethyl-7-oxabicycl o[2.2.1]heptane of the formula VI ##STR34## D. the latter being reacted with a triarylphosphine, and a strong acid to give a mixture of the C.sub.15 -triarylphosphonium salt of the formula III and the novel isomer of the formula iso-III ##STR35## where Ar is an aryl radical, and X is one equivalent of an anion of a strong acid, andE. in each case about 2 mol of the resulting mixture of the C.sub.15 -triarylphosphonium salt III and the novel iso-III being converted by a double Wittig reaction with 2,7-dimethyl-2,4,6-octatrienedial of the formula VIII ##STR36## into zeaxanthin of the formula I.