Vitamin a synthesis and intermediates therefor

Claim 1

THE METHOD OF MAKING VITAMIN A WHICH COMPRISES CONDENSING A DIALKYL ACETAL OF ACETOACETALDEHYDE WITH A PROPARGYL HALIDE IN THE PRESENCE OF A MEMBER OF THE GROUP CONSISTING OF ZINC AND MERCURY-ACTIVATED MAGNESIUM AND THEREBY FORMING THE CARBINOL, 1,1-DIALKOXY-3-METHYL-3HYDROXY HEX-5-YNE, CONDENSING SAID CARBINOL WITH B-IONONE BY MEANS OF A GRIGNARD REACTION AND THEREBY FORMING THE ACETYLENIC DIOL, 1,1-DIALKOXY -3,7-DIMETHYL-3,7-DIHYDROXY-9(2,6,6-TRIMETHYL CYCLOHEX -1-ENYL)--NONA8-ENE-5-YNE, PARTIALLY HYDROGENATING SAID ACETYLENIX DIOL TO THE OLEFINIC DIOL, 1,1-DIALKOXY3,7-DIMETHYL-3,7-DIHYDROXY-9-(2,6,6-TRIMETHYL CYCLOHEX-1-ENYL)-NONA-5,8-DIENE, AND CONVERTING SAID OLEFINIC DIOL TO VITAMIN A ALCOHOL, SAID CONVERTING COMPRISING DEHYDRATING AND HYDROLYZING SAID OLEFINIC DIOL TO THE ALDEHYDE, 3,7-DIMETHYL-9-(2,6,6-TRIMETHYL CYCLOHEX2-ENE-1-YLIDENE)-NONA-2,4,6-TRIENE-1-AL, AND TREATING SAID ALDEHYDE WITH A BASIC REDUCING AGENT AND THEREBY REARRANGING AND REDUCING SAID ALDEHYDE TO VITAMIN A ALCOHOL.