848362-81-2Relevant articles and documents
A new route to vitamin E Key-intermediates by olefin cross-metathesis
Malaise, Gregory,Bonrath, Werner,Breuninger, Manfred,Netscher, Thomas
, p. 797 - 812 (2007/10/03)
Ru-Catalyzed olefin cross-metathesis (CM) has been successfully applied to the synthesis of several phytyl derivatives (2b, 2d-f, 3b) with a trisubstituted C=C bond, as useful intermediates for an alternative route to α-tocopheryl acetate (vitamin E acetate; 1b) (Scheme 1). Using the second-generation Grubbs catalyst RuCl2(C21H 26N2)(CHPh)PCy3, (Cy = cyclohexyl; 4a) and Hoveyda-Grubbs catalyst RuCl2(C21H26N 2){CH-C6H4(O-iPr)-2} (4b), the reactions were performed with various C-allyl (5a-f, 7a,b) and O-allyl (8a-d) derivatives of trimethylhydroquinone-1-acetate as substrates. 2,6,10,14-Tetramethylpentadec-1-ene (6a) and derivatives 6c-e of phytol (6b) as well as phytal (6f) were employed as olefin partners for the CM reactions (Schemes 2 and 5). The vitamin E precursors could be prepared in up to 83% isolated yield as (E/Z)-mixtures.