A new approach to cyclopentitols using CrCl2 mediated domino reaction and ring closing metathesis. The synthesis of 4a-carba-β-d-arabinofuranose and 4a-carba-β-d-lyxofuranose

An efficient method for the syntheses of cyclopentitols from d-ribose is described using Nozaki–Hiyama–Kishi conditions and ring closing metathesis. In this transformation ω-deoxy-ω-iodo ribofuranoside undergoes reductive elimination in the presence of CrCl2 to give the corresponding olefin-aldehyde, which was trapped by a nucleophile under the same conditions to afford the desired diolefinic species. The ring closing metathesis reaction on the diolefinic species with a Grubbs second generation catalyst produced the required carbocycles.

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(3aS,4R,6aR)-2,2-Dimethyl-5-((tetrahydro-2H-pyran-2-yloxy)methyl)-4,6a-dihydro-3aH-cyclopenta[d][1,3]dioxol-4-olC14H22O5[α]D25=-35.8 (c 1.78, CHCl3)Source of chirality: d-riboseAbsolute configuration: (3aS,4R,6aR)

(3aS,4S,6aR)-2,2-Dimethyl-5-((tetrahydro-2H-pyran-2-yloxy)methyl)-4,6a-dihydro-3aH-cyclopenta[d][1,3]dioxol-4-olC14H22O5[α]D25=+3 (c 0.51, CHCl3)Source of chirality: d-riboseAbsolute configuration: (3aS,4S,6aR)

(3aR,6aR)-2,2-Dimethyl-5-((tetrahydro-2H-pyran-2-yloxy)methyl)-3aH-cyclopenta[d][1,3]dioxol-4(6aH)-oneC14H20O5[α]D25=-5 (c 0.85, CHCl3)Source of chirality: d-riboseAbsolute configuration: (3aR,6aR)

(3aS,4S,5R,6aR)-2,2-Dimethyl-5-((tetrahydro-2H-pyran-2-yloxy)methyl)-tetrahydro-3aH-cyclopenta[d][1,3]dioxol-4-olC14H24O5[α]D25=-10.6 (c 0.175, CHCl3)Source of chirality: d-riboseAbsolute configuration: (3aS,4S,5R,6aR)

(1R,2R,3S,4R)-4-(Acetoxymethyl)cyclopentane-1,2,3-triyl triacetateC14H20O8[α]D25=-6 (c 0.465, CH2Cl2)Source of chirality: d-riboseAbsolute configuration: (1R,2R,3S,4R)

(3aS,4R,5R,6aR)-2,2-Dimethyl-5-((tetrahydro-2H-pyran-2-yloxy)methyl)-tetrahydro-3aH-cyclopenta[d][1,3]dioxol-4-olC14H24O5[α]D25=-62 (c 0.25, CHCl3)Source of chirality: d-riboseAbsolute configuration: (3aS,4R,5R,6aR)

(1R,2R,3S,4R)-4-(Hydroxymethyl)cyclopentane-1,2,3-triolC6H12O4[α]D25=-8 (c 0.4, MeOH)Source of chirality: d-riboseAbsolute configuration: (1R,2R,3S,4R)

(1R,2R,3R,4R)-4-(Hydroxymethyl)cyclopentane-1,2,3-triolC6H12O4[α]D25=+6 (c 0.4, MeOH)Source of chirality: d-riboseAbsolute configuration: (1R,2R,3R,4R)

(1R,2R,3R,4R)-4-(Acetoxymethyl)cyclopentane-1,2,3-triyl triacetateC6H12O4[α]D25=-4.5 (c 1.59, CHCl3)Source of chirality: d-riboseAbsolute configuration: (1R,2R,3R,4R)