Enantioselective Synthesis of Chromans for the Preparation of Enantiopure Vitamin E and Analogues
- 1 August 1997
- journal article
- research article
- Published by Georg Thieme Verlag KG in Synthesis
- Vol. 1997 (08) , 877-885
- https://doi.org/10.1055/s-1997-1278
Abstract
Coupling of the different protected (hydroxymethyl)enynes 11a-e and 12a-c with the iodoarene 7 in the presence of catalytic amounts of Pd(PPh3)4 afforded the arylenynes 5a-e and 6a-c which were transformed into the monoprotected chiral trihydroxy compounds 13a-d and 14a,b by Sharpless bishydroxylation with >95% ee for 13a-d, 91% ee for 14b and 64% ee for 14a. A 5-step transformation of 13a led to the desired chroman derivative 3a which was cleaved to give the aldehyde 2 a known precursor for the enantioselective synthesis of vitamin E.Keywords
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