ChemInform Abstract: Transformations of Unsaturated Acyclic Sugars into Enantiomerically Pure Norbornene Derivatives.

Abstract

Abstract The C 7 acyclic unsaturated-sugar ester 1 , derived from l -arabinose, and its enantiomer serve as convenient dieneophiles for chirality transfer for synthesis of optically pure carbocyclic derivatives through cycloaddition reactions. Reaction of 1 with cyclopentadiene may be controlled to give preparative access to the 5,6-disubstituted norbornene adducts 4a , 5a , and 7a , according to the conditions used. The distribution of the four possible isomeric products from this cycloaddition was quantitated, and the effect of substitutional variation on the precursor dienophile 1 was also examined. Adducts 4a and 5a were transformed into such substituted carbocycles of known absolute configuration as the methyl esters ( 11 and 12 ) of norbornene (bicyclo[2.2.1]hept-2-ene)-6-carboxylic acid and nortricyclane (tricyclo[2.2.1.0 2,6 ]heptane)-3-carboxylic acid in optically pure form, specifically through decarbonylation reactions using RhCl(PPh 3 ) 3 (Wilkinson's complex) and [Rh(dppp) 2 ]Cl[dppp = Ph 2 P(CH 2 ) 3 PPh 2 ]. The optical purity of 12 was established by the use of a chiral lanthanide shift-reagent.