L,2,6-Tri-

Selective replacement of hydroxyl groups by bromine has been reported for some inositols and inosamines. DL-2-Amino-2-deoxy-epi-inositol hydrochloride plus acetyl bromide in acetic anhydride gave, after 6 hours at 150°, DL-4-acetamido-l,2,6-tri-0-acetyl-3,5-dibromo-3,4,5-trideoxy-c/uro-inositol in 32% yield, the bromine atoms having been introduced with inversion.407 Under related conditions, DL-epi-... 

Chemical Name D-myo-Inositol l,2,6-tris(dihydrogen phosphate) pentasodium salt... 

P-1,2,4,6-Tetra-O-galloyl-D-glucose (gallotannin) P-l,2,6-Tri-Ogalloyl-I> glucose (gallotannin)... 

S,2S iS,4S,6Ryform 6-Amino-l, 2,6-tri-deoxy-2-(hydroxymethyl) i>2i [o-inositol, 9CL Galacto-validamine. 52L-Carba a-D-galactopyranosylamine [191740-47-3]... 

This method can be considered as a general one except when the preparation of methylmercapto derivatives is not possible, e.g., with 6-benzyl-2,4-dimethyl-3-thioxo-5-oxo-2,3,4,5-tctrahydro-l,2,4-tri-azine which was converted to the corresponding, dioxotriazine derivative by oxidation with bromine in an alkaline solution. ... 

A-methylcyanamido)pyrimidine 136 (85KGS421) (Scheme 52). Attempted desulfurization of 7-methyl-3-propyl-2-thioxo-l,2,4-tri-... 

In similar manner 3,6-dideoxyhexoses have been prepared from esteri-fied 6-deoxy-2-hydroxyglycals. 2,3,4-Tri-0-acetyl-6-deoxy-2-hydroxy-D-glucal was converted into the a and / forms of l,2,4-tri-0-acetyl-2,3-didehydro-3,6-dideoxy-D-en/t/iro-hexose. The a anomer was the main product (77%, 55% isolated crystalline) and, in addition to the ft anomer (19%), a small amount (4%) of saturated products was obtained. On hydrogenation, the major product also suffered some hydrogenolysis but afforded two tri-0-acetyl-3,6-dideoxyhexoses which were shown by NMR spectroscopy to be present in the ratio 12 13 and to have the a configuration. Deacetylation of the reduction products gave... 

The sole recent example in this category is the condensation (in hot aqueous ethanolic sodium hydrogen carbonate) of o-phenylenediamine (399) with tri-tert-butyl 2-hydroxy-3-oxo-l,2,6-piperidinetricarboxylate (400) to give tert-butyl 3-[3-(tcrt-butoxycarbonyl)-3-(tcrt-butoxycarbonylamino)propyl]-2-quinoxalinecarboxy-late (401) in 87% yield.276... 

C15H2o010 l,4,6-Tri-0-acetyl-3-0-(D-l-carboxyethyl)-/ -D-glucopyran-ose-2,l1-lactone (ACEGLL)86... 

C16H21N09 l,4,6-Tri-0-acetyl-2-(N-acetylacetamido)-2,3-dideoxy-a-D- erythro-hex-2-enopyranose ALFABR10 43 243... 

Ci9H25OgP l,2,4-Tri-0-acetyl-5,6-dideoxy-3-0-methyl-5-[(S)-phenyl- phosphinyl]-/ -D-glucopyranose TAMPGP 38 526... 

Monomeric carbene complexes with 1 1 stoichiometry have now been isolated from the reaction of 4 (R = Bu, adamantyl or 2,4,6-trimethylphenyl R = H) with lithium l,2,4-tris(trimethylsilyl)cyclo-pentadienide (72). The crystal structure of one such complex (R = Bu) revealed that there is a single cr-interaction between the lithium and the carbene center (Li-C(carbene) 1.90 A) with the cyclopentadienyl ring coordinated in an if-fashion to the lithium center. A novel hyper-valent antimonide complex has also been reported (73). Thus, the nucleophilic addition of 4 (R = Mes R = Cl) to Sb(CF3)3 resulted in the isolation of the 1 1 complex with a pseudo-trigonal bipyramidal geometry at the antimony center. 

Attachment of the adamantyl group to the ring nitrogen atoms of 3,6-disubstituted [l,2,4]triazolo[5, l-c][l,2,4]tri-azines 51 has been studied by Ulomskii et al. <2002ZOR294> (Scheme 7). These authors found that two products, the A-3-adamantyl 52 and the iV-4-adamantyl compounds 53, can be formed, and the regioselectivity was found to markedly depend on the substituents. Thus, the 2-unsubstituted compound yielded 52 as the only product, whereas 2-methyl and 2-methylsulfano derivatrives afforded 4-adamantyl products 53 in poor to medium yields. 

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