Synthesis of chiral 2-furyl and 3-nitro-7-oxabicyclo[2.2.1]heptane derivatives from sugars

Asymmetric Diels–Alder reactions between 2-methylfuran and chiral (E)-1,2-dideoxy-1-nitroalkenes derived from d-mannose and d-galactose were carried out at room temperature, under 13 kbar pressure. The processes were completely regioselective, and only the four adducts with penta-O-acetyl-1′-C-(4-methyl-3-nitro-7-oxabicyclo[2.2.1]hept-5-en-2-yl)pentitols structures were formed in each case. These adducts, as well as those arising from cycloadditions of the same nitroalkenes and furan, have been converted into chiral derivatives, such as 2-furyl substituted 1-nitrosugars, 2-glyco-4-methyl-3-nitro-7-oxabicyclo[2.2.1]heptanes, and 5,6-exo-epoxy-2-glyco-3-nitro-7-oxabicyclo[2.2.1]hept-5-enes.

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(2R,3R)-1′,2′,3′,4′,5′-Penta-O-acetyl-1′-C-(4-methyl-3-endo-nitro-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl)-d-galacto-pentitolC22H29NO13[α]D = +27.3 (c 1.33, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R)

3,4,5,6,7-Penta-O-acetyl-1,2-dideoxy-(2S)-(5′-methyl-2′-furyl)-1-nitro-d-manno-heptitolC22H29NO13[α]D = +5.1 (c 0.28, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S)

3,4,5,6,7-Penta-O-acetyl-1,2-dideoxy-(2R)-(5′-methyl-2′-furyl)-1-nitro-d-manno-heptitolC22H29NO13[α]D = +40.4 (c 0.52, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R)

3,4,5,6,7-Penta-O-acetyl-1,2-dideoxy-(2S)-(5′-methyl-2′-furyl)-1-nitro-d-galacto-heptitolC22H29NO13[α]D = −18.5 (c 0.41, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S)

3,4,5,6,7-Penta-O-acetyl-1,2-dideoxy-(2R)-(5′-methyl-2′-furyl)-1-nitro-d-galacto-heptitolC22H29NO13[α]D = +10.2 (c 0.43, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R)

(2E)-2-[(2′E)-2′-penten-1′,4′-dione-1′-yl]-4,5,6,7-tetra-O-acetyl-d-lyxo-tetritol-2-heptenose oximeC20H25NO11[α]D = +17.5 (c 0.40, CHCl3)Source of chirality: asymmetric synthesis

(2S,3S)-1′,2′,3′,4′,5′-Penta-O-acetyl-1′-C-(4-methyl-3-endo-nitro-7-oxabicyclo[2.2.1]heptan-2-exo-yl)-d-galacto-pentitolC22H31NO13[α]D = +94.1 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S)

(2R,3R)-1′,2′,3′,4′,5′-Penta-O-acetyl-1′-C-(4-methyl-3-exo-nitro-7-oxabicyclo[2.2.1]heptan-2-endo-yl)-d-galacto-pentitolC22H31NO13[α]D = −15.6 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R)

(2R,3R)-1′,2′,3′,4′,5′-Penta-O-acetyl-1′-C-(5,6-exo-epoxy-3-endo-nitro-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl)-d-galacto-pentitolC21H27NO14[α]D = +56.4 (c 0.22, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R)

(2R,3R)-1′,2′,3′,4′,5′-Penta-O-acetyl-1′-C-(5,6-exo-epoxy-3-endo-nitro-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl)-d-manno-pentitolC21H27NO14[α]D = +35.6 (c 0.50, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R)

(2S,3S)-1′,2′,3′,4′,5′-Penta-O-acetyl-1′-C-(5,6-exo-epoxy-3-endo-nitro-7-oxabicyclo[2.2.1]hept-5-en-2-exo-yl)-d-manno-pentitolC21H27NO14[α]D = −31.1 (c 0.52, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,3S)