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The ring opening of 2α,3α- and 2β,3β-epoxy-5α-androstan-17-one with halide reagents (AlCl3, TMSCl, LiCl, and LiBr) was investigated using imidazolium ionic liquids in the dual role of solvent and catalyst. The application of the ionic liquid was shown to result in an increase in the amount of the unusual diequatorial halohydrins especially at temperatures above 100 °C. With a careful choice of reaction conditions, the latter derivatives could be produced with 43–96% selectivity depending on the nature of the halide ion. Moreover, the usual diaxial products could also be isolated in 70–85% yields by a proper change in the reaction conditions. The reusability of the ionic liquid was demonstrated in both types of reactions. The structures of the products were proved unequivocally by nuclear magnetic resonance (NMR) measurements including two-dimensional (2D) techniques as well as high-resolution mass spectrometry (HRMS). Based on quantum chemical calculations, the effect of the ionic liquid could be explained by the stabilization of the transition state leading to the diequatorial product.

Phosphinooxazoline (PHOX) ligands are an important class of ligands in asymmetric catalysis. We synthesized ten novel D-fructose-derived spiro-fused PHOX ligands with different steric and electronic demand. The application of two of them was tested in asymmetric allylic alkylation. The ligands are prepared in two steps from readily available 1,2-O-isopropylidene protected β-D-fructopyranoses by the BF3·OEt2-promoted Ritter reaction with 2-bromobenzonitrile to construct the oxazoline moiety followed by Ullmann coupling of the resulting aryl bromides with diphenylphosphine. Both steps proceeded mostly in good to high yields (57–86% for the Ritter reaction and 35–89% for the Ullmann coupling). The Ritter reaction gave two anomers, which could be separated by column chromatography. The prepared ligands showed promising results (er of up to 84:16) in Tsuji–Trost reactions with diphenylallyl acetate as model substrate.

Condensation of 1, 6 : 2, 3-dianhydro-β-D-mannopyranose with 2-methyl-(3, 4, 6-tri-O-acetyl-1, 2-dideoxy-α-D-glucopyrano)-[2', 1' : 4, 5]-2-oxazoline (2) in the presence of a catalytic amount of anhydrous p-toluenesulfonic acid in boiling 1, 2-dichloroethane afforded crystalline 4-O-(2-acetamido-3, 4, 6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-1, 6 : 2, 3-dianhydro-β-D-mannopyranose (3) in 42% yield. Azidolysis of the oxirane ring of 3, reduction of the azido to an amino group, and N-acetylation afforded 2-acetamido-4-O-(2-acetamido-3, 4, 6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-3-O-acetyl-1, 6-anhydro-2-deoxy-β-D-glucopyranose (6) in 50% yield. Compound 6 was indistinguishable from the product prepared in 52.2% yield by direct condensation of 2-acetamido-3-O-acetyl-1, 6-anhydro-2-deoxy-β-D-glucopyranose with 2. Acetolysis of 6 provided the title disaccharide.

The title new reducing disaccharide (12) was synthesized starting from 1, 6-anhydro-β-lactose. Selective benzoylation of 1, 6-anhydro-4', 6'-O-benzylidene-β-lactose with 4 molar equivalents of benzoyl chloride in pyridine afforded the corresponding 2, 3, 3'-tri-O-benzoate (3) in 41% yield. Sulfonylation of 3 gave 2'-O-mesylate (4) or 2'-O-tosylate (6). Treatment of 4 or 6 with 1.1 molar equivalents of sodium methoxide in boiling MeOH yielded 1, 6-anhydro-4-O-(2, 3-anhydro-4, 6-O-benzylidene-β-D-talopyranosyl)-β-D-glucopyranose (7) in 50 or 66% yield. Further crop of 7 was isolated from the filtrate of 7 as the corresponding diacetate. Heating of a mixture of 7 with excess aq. KOH at 100° for 3 hr cleaved the epoxide ring of 7 trans-diaxially and, after acetylation, 2, 3-di-O-acetyl-1, 6-anhydro-4-O-(2, 3-di-O-acetyl-4, 6-O-benzylidene-β-D-idopyranosyl)-β-D-glucopyranose (9) was isolated in 84% yield. Debenzylidenation of 9 followed by acetylation, and subsequent opening of the 1, 6-anhydro-β-ring with titanium tetrachloride in CHCl3, then treatment with mercuric acetate in glacial AcOH, afforded 1, 2, 3-tri-O-acetyl-4-O-(2, 3, 4, 6-tetra-O-acetyl-β-D-idopyranosyl)-β-D-glucopyranose (11) in 43% yield. Deacetylation of 11 afforded the title compound (12) as a hygroscopic, amorphous powder which gave the crystalline tosylhydrazone.

On reaction with hypobromous acid, the unsaturated alcohol IIIa yields the diequatorial bromo epoxide XIX arising from the 5α,6α-bromonium ion XVIIIa on cleavage at C(5) by 19b-hydroxyl group with 6(O)n participation. By contrast, the bromonium ion XVIIIb generated from the unsaturated methyl ether IIIb is cleaved by water as external nucleophile to yield the unstable diaxial bromohydrin XX which undergoes cyclization to the oxirane derivative XXI. A comparison with the reaction course in homologs of the type I and II permits the conclusion that the change in regioselectivity, generally possible outcome of the 5(O)n participation, is only possible for the 6(O)n process if the participating group is a hydroxyl.