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Novel vitamin E intermediates and process for the preparation of (2R, 4'RS)- alpha -tocopherol and (all-rac)- alpha -tocopherol via the novel intermediates
Novel vitamin E intermediates and process for the preparation of (2R, 4'RS)- alpha -tocopherol and (all-rac)- alpha -tocopherol via the novel intermediates
Compounds of the general formula I IMAGE in which R1 denotes H, an alkyl radical, arylalkyl radical or an aliphatic acyl radical, preferably a benzyl group or acetyl group, and Y represents OH and X represents H (Ia) or else X and Y together represent a further bond between the C atoms carrying X and Y (Ib) and the dashed line may denote an additional bond, in particular [2R,1'Z,3'E,7'E]-6-benzyloxy-2,5,7,8-tetramethyl-2-(4',8',12'- trimethyltrideca-1',3',7'-trien-1'-yl)chroman and 6-benzyloxy-2,5,7,8- tetramethyl-2-(1'-hydroxy-4',8',12'-trimethyltrideca-3',7'-dien-1-yl)- chroman, and compounds of the general formula II IMAGE in which Z represents one of the groups ClMg-; BrMg- (IIa); CL(-))C6H5)3P(+); BR(+))C6H5)3P(+)- (IIb in which R2 represents alkyl having 1 to 4 C atoms, in particular (3,7,11-trimethyltrideca-2,6,10-trien-1-yl)triphenylphosphonium chloride and dimethyl (3,7,11-trimethyltrideca-2,6,10-trien-1-yl)- phosphite. The invention furthermore relates to a process for the preparation of (2R,4'RS,8'RS)- alpha -tocopherol or (all-rac)- alpha -tocopherol, starting from the compounds of the formula II and via the compounds of the formula I.
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