Creation of quarternary stereocentres via [3,3]-sigmatropic rearrangement of allylic thiocyanates. A synthetic approach to (+)-myriocin

A stereoselective approach to the advanced precursor of (+)-myriocin, 3-deoxy-1,2:5,6-di-O-isopropylidene-3-methoxycarbonylamino-α-d-glucofuranose 3-C-carboxylic acid, via the [3,3]-sigmatropic rearrangement of allylic thiocyanates prepared from d-glucose is presented. From the observed results, supported by DFT calculations, we can conclude that the [3,3]-sigmatropic rearrangement of the thiocyanato group in allylic hexofuranosides is strongly influenced by the steric interaction of the 1,2-O-isopropylidene group in the transition states.

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3-Deoxy-1,2:5,6-di-O-isopropylidene-3-methoxycarbonylamino-α-d-glucofuranose 3-C-carboxylic acidC15H23NO9[α]D25=+86 (c 0.195, CHCl3)Source of chirality: d-glucose1R,2R,3R,4S,5R

3-C-(Z)-Carbomethoxymethylene-3-deoxy-1,2-O-isopropylidene-α-d-glucofuranoseC12H18O7[α]D25=+126.5 (c 0.29, CHCl3)Source of chirality: d-glucose1R,2R,4S,5R

5,6-Bis(O-tert-butyldimethylsilyl)-3-deoxy-3-C-(Z)-(2-hydroxyethylidene)-1,2-O-isopropylidene-α-d-glucofuranoseC23H46O6Si2[α]D25=+67.3 (c 0.13, CHCl3)Source of chirality: d-glucose1R,2R,4S,5R

5,6-Bis(O-tert-butyldimethylsilyl)-3-deoxy-1,2-O-isopropylidene-3-isothiocyanato-3-C-vinyl-α-d-glucofuranoseC24H45NO5SSi2[α]D25=+21.3 (c 0.13, CHCl3)Source of chirality: d-glucose1R,2R,3R,4S,5R

3-Deoxy-1,2:5,6-di-O-isopropylidene-3-isothiocyanato-3-C-vinyl-α-d-glucofuranoseC15H21NO5S[α]D25=+51.1 (c 0.23, CHCl3)Source of chirality: d-glucose1R,2R,3S,4S,5R

3-Deoxy-1,2:5,6-di-O-isopropylidene-3-methoxythiocarbonylamino-3-C-vinyl-α-d-glucofuranoseC16H25NO6S[α]D25=+16.3 (c 0.18, CHCl3)Source of chirality: d-glucose1R,2R,3S,4S,5R

3-Deoxy-1,2:5,6-di-O-isopropylidene-3-methoxycarbonylamino-3-C-vinyl-α-d-glucofuranoseC16H25NO7[α]D25=+31.4 (c 0.26, CHCl3)Source of chirality: d-glucose1R,2R,3S,4S,5R

3-Deoxy-1,2:5,6-di-O-isopropylidene-3-methoxycarbonylamino-α-d-glucopyranose 3-C-carbaldehydeC15H23NO8[α]D25=+46.3 (c 0.16, CHCl3)Source of chirality: d-glucose1R,2R,3R,4S,5R