Branched-chain sugars with organometallic reagents

The reaction of hex-l-enopyran-3-ulose derivatives with organometallic reagents to give branched-chain sugars with reasonable 7c-facial selectivity has been disclosed (Scheme 3). Thus the use of titanium reagents on the D-erythro-corapound (9) gave... 

Reaction of Free Carbonyl Sugar Derivatives with Organometallic Reagents. II. 6-Deoxy-L-idose and a Branched-Chain Sugar, M. L. Wolfrom and S. Hanessian,/. Org. Chem., 27, 2107-2109 (1962). 

Stereodivergent pathways relative to other allylic systems (e.g. allylic acetates) have been found in the reactions of cyclic allylic sulfides or ethers of benzothiazole with organocopper reagents. In this case the Sn2 process occurs with syn stereochemistry (eq 5) and is due to the anchimeric coordination of the organometallic reagent with the heterocyclic moiety. This has been utilized for regio- and stereocontroUed access to branched-chain sugars. 

The reaction of various organometallic reagents with the ketone (21) leading to the branched-chain sugars (22) has been described (Scheme 6)." The products were used to prepare cyclopentane fused isoxazolidines (23) by a nitrone-alkene cycloaddition process (see Clhapter 18). 

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