Stereocontrolled synthesis of conformationally restricted enantiopure triols and dihydroxy acids based on the norbornane framework

The synthesis of chiral, rigid analogues of glycerol and cyclitols has been achieved by means of the stereocontrolled reduction of chiral bridgehead-substituted camphorquinones. This simple and easy procedure exclusively affords dihydroxy derivatives with a 2,3-cis-exo-configuration. The employment of different hydrides has also allowed the synthesis of enantiopure 2,3-dihydroxy carboxylic acids with high diastereoselectivity.

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7,7-Dimethyl-2,3-dioxobicyclo[2.2.1]hept-1-yl trifluoromethanesulfonateC10H11F3O5S[α]D20=+275.1 (c 0.92, CH2Cl2)Source of chirality: natural (1R)-fenchoneAbsolute configuration: 1R

7,7-Dimethylbicyclo[2.2.1]heptane-1,2,3-triolC9H16O3[α]D20=+16.0 (c 0.99, MeOH)Source of chirality: natural (1R)-fenchoneAbsolute configuration: 1R,2S,3S

2,3-Dihydroxy-7,7-dimethylbicyclo[2.2.1]heptane-1-carboxylic acidC10H16O4[α]D20=-18.2 (c 0.50, MeOH)Source of chirality: natural (1R)-camphorAbsolute configuration: 1S,2S,3R

1-(Hydroxymethyl)-7,7-dimethyl-bicyclo[2.2.1]heptane-2,3-diolC10H18O3[α]D20=-27.7 (c 1.04, MeOH)Source of chirality: natural (1R)-camphorAbsolute configuration: 1R,2S,3R