Studies on epoxidation of enantiomerically pure 2,3-dideoxy hex-2-enitols: a convenient access to highly functionalized enantiomerically pure tetrahydrofuran derivatives

A detailed comparative study on the epoxidation of enantiomerically pure allylic alcohols 8–14 derived from their respective glycals with Sharpless, m-CPBA and Camp’s reagents was carried out in order to obtain 2,3-epoxy alcohols keeping in view the versatility of these synthons in synthetic chemistry for the preparation of various molecules of biological importance by suitable chemical transformations. During the course of this study, the Sharpless asymmetric epoxidation reaction was found to be an unprecedented alternative, due to its mild reaction conditions, for synthesizing highly functionalized enantiomerically pure tetrahydrofuran derivatives. A detailed mechanistic pathway of their formation has also been studied.

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(2S,3R)-4,6-Di-O-benzyl-2,3-epoxy-d-galactitolC20H24O5De >99%[α]D = −26.5 (c 0.170, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3R,4S,5R)

(2R,3S)-4,6-Di-O-benzyl-2,3-epoxy-d-galactitolC20H24O5De >99%[α]D = −16.4 (c 0.073, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3S,4S,5R)

(2S,3R)-4,6-Di-O-benzyl-2,3-epoxy-d-glucitolC20H24O5De >99%[α]D = +12.1 (c 0.066, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3R,4R,5R)

(2S,3R)-4,5,6-Tri-O-benzyl-2,3-epoxy-d-galactitolC27H30O5De >99%[α]D = −20.3 (c 0.123, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3R,4S,5R)

(2R,3S)-4,5,6-Tri-O-benzyl-2,3-epoxy-d-glucitolC27H30O5De >99%[α]D = −22.8 (c 0.136, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3S,4R,5R)

(2S,3R)-4,5,6-Tri-O-benzyl-2,3-epoxy-d-glucitolC27H30O5De >99%[α]D = +10.52 (c 0.057, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3R,4R,5R)

3,6- Anhydro-4,5-di-O-benzyl-d-galactitolC20H24O5De >99%[α]D = +25.0 (c 0.140, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S,4S,5R)

3,6-Anhydro-1,2-di-O-acetyl-4,5-di-O-benzyl-d-galactitolC22H26O6De >99%[α]D = +15.55 (c 0.090, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S,4S,5R)

3,6-Anhydro-4,5-di-O-benzyl-l-galactitolC20H24O5De >99%[α]D = +2.0 (c 0.100, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R,4S,5R)

3,6-Anhydro-1,2-di-O-acetyl-4,5-di-O-benzyl-l-galactitolC22H26O6De >99%[α]D = +19.1 (c 0.068, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R,4S,5R)