Three Threitol derivative

Synthesis from L-threitol The L-threitol derivative 24, obtained from D-(-)-diethyl tartarate in three steps and 90% overall yield, was used as a starting material for the synthesis of nectrisine (1) (Scheme 5). " Swern oxidation of 24 produced the L-threose derivative 25, which was transformed into the aminonitrile 26 in 96% overall yield from 24, as an inseparable diastereomeric mixture. Removal of the silyl protecting group from 26 followed by oxidation of the resulting primary hydroxyl group with TPAP afforded the lactam 27, which was treated with sodium methoxide to produce the methyl ester 28 in 62% yield from 26. Lithium borohydride reduction of 28 afforded a chromatographically separable mixture of the lactams 29 and 30 in a ratio of 56 44 and 87% total yield. Silylation... 

The diversity associated with silyl protecting groups as well as the chemical conditions available for their removal makes them attractive alternatives to benzyl protection of the hydroxy groups of either D- or L-tartaric acid derivatives. O-isopropylidene-L-threitol (37) is mono-protected with er -butyldimethylsilyl chloride to furnish 266, which is converted in three steps to the nitrile 267. Reduction with DIBAL and Wittig olefination followed by desilylation with fluoride and Swern oxidation of the resulting alcohol provides aldehyde 268, which reacts with methyl 10-(triphenylphosphorane)-9-oxo-decanoate (269) to afford enone 270. Reduction of 270 with subsequent preparative TLC and acetal hydrolysis furnishes (9R)-271 and (9 S)-272, both interesting unsaturated trihydroxy Cig fatty acid metabolites isolated from vegetables [91] (Scheme 62). 

Aldotetrose B must be D-threose because the alditol derived from it (o-threitol) is optically active (the alditol from D-erythrose, the other possible D-aldotetrose, would be meso). Due to rotational symmetry, however, the alditol from B (D-threitol) would produce only two NMR signals. Compounds A-F are thus in the family of aldoses stemming from D-threose. Since reduction of aldopentose A produces an optically inactive alditol, A must be D-xylose. The two diastereomeric aldohexoses C and D produced from A by a Kiliani-Fischer synthesis must therefore be D-idose and D-gulose, respectively. E and F are the alditols derived from C and D, respectively. Alditol E would produce only three C NMR signals due to rotational symmetry while F would produce six signals. 

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