The synthesis of (+)-nemorensic acid in nine steps is described; key steps in the route were the stereoselective Birch reduction of a substituted furan, and addition of allyltrimethylsilane to an oxonium ion at C-5; an X-ray crystal structure of (2)-nemorensic acid provided proof of the relative stereochemistry of the target.

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Silyl-Substituted Furans in the Stereoselective Birch Reduction. -Chiral 2-furoic acid amide (V) bearing a silicon group ortho to the chiral auxiliary is prepared and subjected to a Birch reductive alkylation giving dihydrofurans (VII) with high levels of diastereoselectivity. -(DONOHOE, TIMOTHY J.; GUILLERMIN, JEAN-BAPTISTE; CALABRESE, ANDREW A.; WALTER, DARYL S.; Tetrahedron Lett. 42 (2001) 34, 5841-5844; Dep. Chem., Univ. Manchester, Manchester M13 9PL, UK; EN)