Yoshifusa Tachimori

Stereoselective nucleophilic addition reactions to nitro sugars

Nucleophile(s) almost exclusively added from the equatorial side of 2-nitro-β-D-2-enopyranoside and the axial side of 2-nitro-D-ribo-1-enitol. On the other hand, methoxide and tert-butyl peroxide ions approached from the equatorial side of 2-nitro-α-D-2-enopyranoside, whereas methanol and hydrogen peroxide ion from the axial side.

Preparation of 4,6-O-benzylidene-2-C- and -3-C-p-tolylsulfonylhex-2-enopyranoside derivatives and a 2-C-p-tolylsulfonylhex-2-enitol derivative

Abstract 4,6- O -Benzylidenehex-2-enopyranoside derivatives having a 2- C - or 3- C-p -tolylsulfonyl group were synthesized from appropriate nitro sugars by the addition of p -toluenesulfinic acid followed by elimination of nitrous acid. 1,5-Anhydro-4,6- O -benzylidene-2,3-dideoxy-2- C-p -tolylsulfonyl- d - erythro -hex-2-enitol was similarly prepared. Methyl 4,6- O -benzylidene-2,3-dideoxy-2- C - and -3- C-p -tolylsulfonyl-α- d - erythro -hex-2-enopyranosides were alternatively ynthesized from methyl 2,3-anhydro-α- d -allo- and -mannopyranosides, respectively, by cleavage of the oxirane ring with sodium p -toluenethiolate, followed by oxidation.

Kinetically controlled nucleophilic addition-reactions to methyl 4,6-O-benzylidene-2,3-dideoxy-2-nitro-α-d-erythro-hex-2-enopyranoside☆

Abstract Axial attack mainly occurred in the reactions of methyl 4,6- O -benzylidene-2,3-dideoxy-2-nitro-α- d - erythro -hex-2-enopyranoside with sodium borodeuteride, hydrogen peroxide, hydrogen cyanide, and methanol, whereas equatorial attack predominated in the reaction with sodium methoxide and tert -butyl peroxide.

Preparation of methyl 4,6-O-benzylidene-2,3-dideoxy-2,3-dinitro-α-D-glucopyranoside and its selective conversion into the corresponding 2-nitro-2-enopyranoside

Abstract Treatment of methyl 4,6- O -benzylidene-2,3-dideoxy-3-nitro-α- D - erythro -hex-2-enopyranoside ( 3 ) with sodium nitrite in benzene-water in the presence of small amounts of tributylhexadecylphosphonium bromide as a phase-transfer catalyst afforded the 2-nitro alkene 4 in 47% yield. A similar reaction in the presence of 1.3 equiv. of acetic acid gave the 2,3-dinitro derivative 5 in 58% yield; it was selectively converted into the 2-nitro alkene 4 . In these reactions, nitrite ion undergoes addition from the axial and equatorial sides of 3 and 4 , respectively.

The Michael reaction of a methyl 2-C-nitro-α-d-hex-2-enopyranoside: Preparation and structural determination of the adducts having the d-altro-, d-gluco, and d-manno configurations

Abstract The reactions of methyl 4,6- O -benzylidene-2,3-dideoxy-2- C -nitro-α- d - erythro -hex-2-enopyranoside ( 1 ) with 2,4-pentanedione and diethyl malonate afforded adducts having the d - altro , d - gluco , and d - manno configurations. Besides the adducts having the d - gluco and d - altro configurations, a 1,5-anhydro-2- C -nitrohex-1-enitol derivative was isolated in the reaction of 1 with dimethyl malonate. The product ratio was found to depend on the solvent. The nucleophilic addition and subsequent protonation appear to be respectively controlled kinetically and thermodynamically.

Novel synthesis of γ-hydroxy-α-nitro-olefins

Treatment of α-unsubstituted αβ-epoxyketoximes with trifluoroperoxyacetic acid affords the corresponding γ-hydroxy-α-nitro-olefins in high yields.