Epoxidation of glycals with oxone–acetone–tetrabutylammonium hydrogen sulfate: a convenient access to simple β-d-glycosides and to α-d-mannosamine and d-talosamine donors

The addition of a phase transfer catalyst during the epoxidation of perbenzylated glycals with oxone–acetone under biphasic conditions allows their complete epoxidation. The epoxides were readily transformed into methyl 1,2-trans-β-d-glycosides or 1,2-trans-β-d-glycopyranosyl azides (d-gluco and-d-galacto configurations) bearing a free hydroxyl group at the 2-position. These glycosyl azides were converted to alkyl 1,2-trans-2-acetamido-2-deoxy-α-d-pyranosides or alkyl 2-allyloxycarbonylamino-2-deoxy-α-d-pyranosides (d-manno and d-talo configurations) by a Staudinger reaction and a double inversion of configuration at C-1 and C-2.

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Methyl 3,4,6-tri-O-benzyl-β-d-glucopyranosideC28H3206[α]D=-4.7[α]D=-4.7 (c 1.0, CHCl3)Source of chirality: d-glucoseAbsolute configuration: (1R,2R,3R,4S,5R)

Methyl 3,4,6-tri-O-benzyl-β-d-galactopyranosideC28H32O6[α]D=-6.4[α]D=-6.4 (c 1.0, CHCl3)Source of chirality: d-galactoseAbsolute configuration: (1R,2R,3R,4R,5R)

Methyl 3,6-di-O-benzyl-4-O-(2,3,4,6-tetra-O-benzyl- α -d-galactopyranosyl)-β-d-glucopyranosideC48H54O11[α]D=+9.6[α]D=+9.6 (c, 1.0, CHCl3)Source of chirality: d-lactoseAbsolute configuration: (1R,2R,3R,4S,5R,1′S,2′R,3′S,4′R,5′R)

3,4,6-Tri-O-benzyl-β-d-glucopyranosyl azideC27H29N3O5[α]D=-5.0[α]D=-5.0 (c 1.0, CHCl3)Source of chirality: d-glucoseAbsolute configuration: (1R,2R,3R,4S,5R)

3,4,6-Tri-O-benzyl-α-d-mannopyranosyl azideC27H29N3O5[α]D=+180.0[α]D=+180.0 (c 1.0, CHCl3)Source of chirality: d-glucoseAbsolute configuration: (1S,2S,3R,4S,5R)

3,4,6-Tri-O-benzyl-β-d-galactopyranosyl azideC27H29N3O5[α]D=-10.7[α]D=-10.7 (c 1.0, CHCl3)Source of chirality: d-galactoseAbsolute configuration: (1R,2R,3R,4R,5R)

3,4,6-Tri-O-benzyl-2-O-mesyl-β-d-glucopyranosyl azideC28H31N3O7S[α]D=-36.9[α]D=-36.9 (c 1.0, CHCl3)Source of chirality: d-glucoseAbsolute configuration: (1R,2R,3S,4S,5R)

3,4,6-Tri-O-benzyl-2-O-mesyl-β-d-galactopyranosyl azideC28H31N3O7S[α]D=-33.1[α]D=-33.1 (c 1.0, CHCl3)Source of chirality: d-galactoseAbsolute configuration: (1R,2R,3S,4R,5R)

Methyl 2-acetamido-3,4,6-tri-O-benzyl-2-deoxy-α-d-mannopyranosideC30H35NO6[α]D=+33.6[α]D=+33.6 (c 1.0, CHCl3)Source of chirality: d-glucoseAbsolute configuration: (1S,2S,2R,4S,5R)

Methyl 2-allyloxycarbonylamino-3,4,6-tri-O-benzyl-2-deoxy-α-d-mannopyranosideC32H37NO7[α]D=+20.0[α]D=+20.0 (c 1.0, CHCl3)Source of chirality: -d-glucoseAbsolute configuration: (1S,2S,2R,4S,5R)

Pentenyl 2-allyloxycarbonylamino-3,4,6-tri-O-benzyl-2-deoxy-α-d-mannopyranosideC36H45NO7[α]D=+21.7[α]D=+21.7 (c 1.0, CHCl3)Source of chirality: -d-glucoseAbsolute configuration: (1S,2S,2R,4S,5R)

Methyl 2-acetamido-3,4,6-tri-O-benzyl-2-deoxy-α-d-talopyranosideC30H35NO6[α]D=+13.5[α]D=+13.5 (c 1.0, CHCl3)Source of chirality: d-galactoseAbsolute configuration: (1S,2S,2R,4R,5R)

N-Acetyl-3,4,6-tri-O-benzyl-2-O-mesyl-β-d-galactopyranosyl amineC30H35NO8S[α]D=+24.8[α]D=+24.8 (c 1.0, CHCl3)Source of chirality: d-galactoseAbsolute configuration: (1R,2R,2S,4R,5R)

Pentenyl 2-allyloxycarbonylamino-3,4,6-tri-O-benzyl-2-deoxy-α-d-talopyranosideC36H45NO7[α]D=+16.3[α]D=+16.3 (c 1.0, CHCl3)Source of chirality: d-galactoseAbsolute configuration: (1S,2S,3R,4R,5R)