Process for the preparation of tocopherols and in particular of d- alpha -tocopherol, intermediates in the process and their use

摘要

A process for the preparation of tocopherols, in particular of d- alpha -tocopherol, in which a carbonyl alkenylcarbene metal complex having substituents R1 and R2 on the alkenyl group and an ether substituent R3, in which R1 represents CH3 or OCH3; R2 represents H, CH3 or OCH3 and R3 represents CH3, C2H5, COR or SiR3, in which R is an alkyl, aryl or alkylaryl, is reacted with an alkynol of the formula (9) IMAGE in which R4 denotes H or CH3; R5 denotes [(CH2)3CHCH3]3CH3, IMAGE where X is H, OH or COOR6 and R6 is lower alkyl, then the metal carbonyl portion is eliminated from the resulting reaction product (10), and the metal-free product (11) is de-etherified and cyclised in the presence of acidic catalysts to give the desired tocopherol. The process permits the stereoselective synthesis of natural tocopherol in high yield with few reaction steps, novel intermediates being formed.