Heizan Kawamoto

Synthesis of 1,2,4-tri-O-acetyl-3,6-di-O-benzyl-5-deoxy-5-C-[(S)-phenylphosphinyl]-β-d-glucopyranose: The first gluco type of hexopyranose derivative having phosphorus in the hemiacetal ring

Abstract Oxidation of 3,6-di- O -benzyl-1,2- O -isopropylidene-α- d -glucofuranose with pyridinium chlorochromate in the presence of molecular sieves, followed by conversion into the p -tolylsulfonylhydrazone, addition of methyl phenylphosphinate, and reduction with sodium borohydride, provided the key intermediate, namely, 5( R , S )-3,6-di- O -benzyl-5-deoxy-1,2- O -isopropylidene-5- C -[(methoxy)phenylphosphinyl]-α- d - xylo -hexofuranose, in 23% overall yield. Treatment of this compound with sodium dihydrobis(2-methoxyethoxy)aluminate, followed by the action of mineral acid and acetic anhydride, yielded the crystalline title compound, the structure of which was established on the basis of mass and 400-MHz, 1 H-n.m.r. spectra. A general dependence of 2 J PH values on the OPCH dihedral angles effectively served for assigning the configuration of C-1, C-5, and the ring-phosphorus atom of the present product and other such 5- C -phosphinylhexopyranoses.

Synthesis of 4,5-dideoxy-4-C-[(R,S)-phenylphosphinyl]-d-ribo- and l-lyxo-furanose and their 1,2,3-triacetates

Abstract 2,3- O -Isopropylidene- d -ribose diethyl dithioacetal, prepared from d -ribose, was converted in three steps into the corresponding dimethyl acetal, which was monotosylated at O-5, and the ester oxidized at C-4 with pyridinium chlorochromate; addition of methyl phenylphosphinate to the resulting pentos-4-ulose derivative then provided (4 R,S )-4,5-anhydro-2,3- O -isopropylidene-4- C -[( R,S )-(methoxy)phenylphosphinyl]- d - erythro -pentose dimethyl acetal. Hydrogenation of this compound in the presence of Raney Ni, followed by reduction with SDMA, hydrolysis, and acetylation, yielded the title compounds (seven kinds), the structures of which were established on the basis of their 400-MHz, 1 H-n.m.r. and mass spectra. A general dependence of the 2 J PH and 3 J PH values on the OPCH and PCCH dihedral angles provided an effective method for the assignment of the configurations and conformations of these 4-deoxy-4-phosphinyl-pentofuranoses.

Synthesis, and x-ray structural analysis, of 1,2,3,4-tetra-O-acetyl-5,6-dideoxy-5-C-[(S)-phenylphosphinyl]-α- and -β-l-idopyranose

Abstract The title compounds and two diastereoisomers were prepared from (5 RS )-3- O -benzyl-5,6-dideoxy-5- C -[( RS )-(ethoxy)phenylphosphinyl]-1,2- O -isopropylidene-α- d - xylo -hexofuranoses upon reduction with sodium dihydrobis(2-methoxyethoxy)-aluminate, followed by hydrolysis with mineral acid, and acetylation with acetic anhydride-pyridine. Among these products, the two readily crystallized compounds were determined by X-ray crystallographic analysis to be 1,2,3,4-tetra- O -acetyl-5,6-dideoxy-5- C -[( S )-phenylphosphinyl]-α- and -β- l -idopyranose- 4 C 1 .

Stereoselectivity in deoxygenation of 5-hydroxy-5-phosphinyl-hexofuranoses (α-hydroxyphosphonates)

The addition of dimethyl phosphonate to six different hexofuranos-5-uloses in the presence of DBU, followed by esterification with methoxalyl chloride and then radical reduction, afforded 5-deoxy-5-dimethoxyphosphinyl-D- and L-hexofuranoses. The stereoselectivity of the deoxygenation and possible transition-state models are discussed.

A new route for preparation of 2-deoxy-D-ribofuranose phospho sugar

The addition reaction of dimethyl phosphonate to (2R,4S)-4-(tertbutyldimethylsilyl)oxymethyl-2-methyl-1,3-dioxan-5-one (11a), followed by dehydroxylation, provided 1-O-(tert-butyldimethylsilyl)-3-deoxy-3-dimethoxyphosphinoyl-2,4-O-ethylidene-D-erythritol (13a). Elongation of carbon skeleton of the D-erythrose (14) derived from 13a and then acidic methanolysis gave a mixture of methyl 2,4-dideoxy-4-dimethoxyphosphinoyl-alpha,beta-D-erythropentopyranosides (7), which was led to 2-deoxy-D-ribofuranose phospho sugar (4) in an appreciably improved total yield compared with the procedures via previously reported route.

Improved syntheses of D-ribo- and 2-deoxy-D-ribofuranose phospho sugars from methyl β-D-ribopyranoside

Methyl 4-deoxy-4-dimethoxyphosphinoyl-2,3-O-isopropylidene-beta-D-ribopyranoside (12a) and methyl 2,4-dideoxy-4-dimethoxyphosphinoyl-beta-D-erythro-pentopyranoside (20) were efficiently prepared respectively from methyl 2,3-O-isopropylidene-beta-D-ribopyranoside (7a) and its 3,4-O-isopropylidene isomer (7b) in appreciably improved total yields compared with those via previously reported routes. Compounds (12a, 20) were led to D-ribofuranose and 2-deoxy-D-ribofuranose phospho sugars (4, 5).

A Convenient Method for the Preparation of Methyl 2‐Deoxy‐β‐D‐erythro‐pentopyranoside.

Das literaturbekannte Ribopyranosid (Ia) wird uber das Xanthogenat (Ib) wie angegeben zur 2-Desoxyverbindung (IIa) umgesetzt.