Synthesis of Glycosylphosphine Oxides and Related Compounds

Abstract

The benzyl‐protected glycosyl acetates 1, 6, 11, and 15 react with MeOPPh2 under catalysis by TMSOTf to yield diastereoselectively the glycosylphosphine oxides 2, 3, 8, 12, 13, and 16, with a strong preference for the 1,2‐cis‐configurated anomers. Hydrogenolysis of the major products gave the crystalline, unprotected phosphine oxides 4, 9, 14, and 17, of which 4 was transformed in to the acetate 5, and 9 into the benzoate 10. The benzylated phosphine oxides 4, 8, 12, and 16 were reduced with Cl3SiH in the presence of a tertiary amine to form the phosphines 18, 21, 24, and 26, which were transformed into the phosphine sulfides 19, 22, 25, and 27. Moreover, 18 and 21, were characterized as the borane adducts 20, and 23. The structure of the (arabinofuranosyl)phosphine oxide 12, the corresponding sulfide 25, and of the borane complex 20 were established by X‐ray analysis. According to NMR spectroscopy, the equatorial pyranosylphosphine oxide 8, the sulfide 22, and the borane complex 23 adopt a 4C1 conformation. The axial phosphine oxide 2 is a flattened 4C1, the sulfide 19 exists as a B2,5, and the borane complex 20 is a flattened 4C1 in the solid sate and a B2,5 in solution. Thus, the conformational behavior of these α‐D‐glucopyranose derivatives reflects the steric requirement of the P‐substituents.

Glycosylidene Diazirines

“…Generation of the carbene at -78 "C (hv) led in 55% yield to a 74:26 mixture of anomers. Glycosyl phosphine oxides were then prepared from glycosyl acetates by TMSOTf-catalyzed treatment with MeOPPh2 and subsequently reduced to glycosyl phosphines [45]. The benzylated aziglucose 7 and azimannose 19 react with tributyl or triphenyl stannane and yield glycosyl stannanes (Figure 7b) [46].…”

Borane Complexes of Trivalent Organophosphorus Compounds. Versatile Precursors for the Synthesis of Chiral Phosphine Ligands for Asymmetric Catalysis

“…13 In an extension of this work the group of Gaumont recently elaborated the hydrophosphination of methyl acrylate (24) and dimethyl vinylphosphonate (25) as a method for the selective preparation of mono-and disubstituted phosphines. 50 As listed in Table 3 monophosphines 26a and 27a were formed in good yields by the reaction of equimolar amounts of PhPH 2 -BH 3 (23) with the alkene in toluene at room temperature. When more than the double amount of alkene was applied the disubstituted phosphine-borane adducts 26b and 27b, respectively, were produced.…”