- Improved preparations of some per-O-acetylated aldohexopyranosyl cyanides.
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3,4,6-Tri-O-acetyl-1,2-O-[1-(exo-, endo-cyano)ethylidene]-alpha-D- galacto- (1a/b), -alpha-D-gluco- (2a/b), and -beta-D-manno-pyranose (3a/b) were stereoselectively isomerized to the corresponding per-O-acetylated 1,2-trans-aldohexopyranosyl cyanides in 75, 16, and 62% yield, respectively, by treatment with boron trifluoride etherate in dry nitromethane. The corresponding per-O-acetylated 1,2-cis-aldohexopyranosyl cyanides were obtained concurrently in respective yields of 1.9, 0.9, and 4.8%. The per-O-acetylaldohexopyranosyl cyanide products were found stable to the reaction conditions and were readily isolated following completion of the rearrangement. It had previously been proved that reaction of 2,3,4,6-tetra-O-acetyl-alpha-D-manno- and -gluco-pyranosyl bromide with mercuric cyanide in nitromethane generates, in the ratio of approximately 1:1, the desired 1,2-trans-glycosyl cyanides and the corresponding 1,2-O-(1-cyanoethylidene) isomers (3a/b and 2a/b, respectively). Treatment of these reaction-mixtures with boron trifluoride etherate in nitromethane effected the rearrangement of 3a/b and 2a/b, thereby facilitating the isolation, and increasing the overall yields, of the per-O-acetylated 1,2-trans-D-manno- and -gluco-pyranosyl cyanides (58 and 30% total yield, respectively) relative to the earlier procedures. The boron trifluoride etherate-mediated reaction of per-O-acetyl-alpha- and -beta-D-galacto-, -alpha- and -beta-D-gluco-, -alpha-D-manno-, and -2-deoxy-2-phthalimido-beta-D-gluco-pyranoses with trimethylsilyl cyanide in nitromethane was also investigated. This reaction provides a "one-flask" synthesis of the corresponding per-O-acetylated 1,2-trans-aldohexopyranosyl cyanides in which 1,2-O-(1-cyanoethylidene) derivatives are isomerized in situ. Finally, improved preparations of the (not readily accessible) per-O-acetylated 1,2-cis-D-manno- and -gluco-pyranosyl cyanides are described. Thus, 2,3,4,6-tetra-O-acetyl-alpha- and -beta-D-mannopyranosyl cyanide (48 and 16% total yield, respectively) and -alpha- and -beta-D-glucopyranosyl cyanide (12 and 39% total yield, respectively) were synthesized by fusion of the corresponding alpha-D-glycosyl bromides with mercuric cyanide.
- Myers,Lee
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Read Online
- Substrate based PET imaging agents
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The present application is directed to radiolabeled imaging agents comprising a radiolabel, and a substrate, pharmaceutical compositions comprising radiolabeled imaging agents, and methods of using the radiolabeled imaging agents. The present application is further directed to methods of preparing the radiolabeled imaging agent. Such imaging agents can used in imaging studies, such as Positron Emitting Tomography (PET) or Single Photon Emission Computed Tomography (SPECT).
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Page/Page column 44; 45; 46; 49
(2020/11/13)
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- Synthesis of a protected δ-glyco-amino acid building block for incorporation into peptide chains
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The synthesis of a suitably protected sugar amino acid (δ-glyco-amino acid) as a building block to be incorporated into the peptide chain (N-terminus) of bioactive peptide analogues is described. Its efficient coupling reactions with pilot amino acids as
- Paloumbis, George,Petrou, Christos C.,Nock, Berthold,Maina, Theodosia,Pairas, George,Tsoungas, Petros G.,Cordopatis, Paul
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p. 845 - 852
(2008/01/06)
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- Solid-phase synthesis of cyclic C-glycoside/amino acid hybrids by carbamate coupling chemistry and on-support cyclization
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A solid-supported synthesis of cyclic C-glycoside/amino acid conjugates is described. For this purpose, N-(tert-butoxycarbonyl)-[6-O-(p- nitrophenoxycarbonyl)-2,3,4-tri-O-(p-toluoyl)-β-D-glycopyranosyl] methylamines derived from galactose and glucose were
- Katajisto, Johanna,Loennberg, Harri
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p. 3518 - 3525
(2007/10/03)
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- (-)-Daucic acid: Proof of D-lyxo configuration, synthesis of its D-ribo, D-xylo, L-arabino and L-lyxo analogs, and biosynthetic implications
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The dimethyl esters of the 2,6-anhydro-3-deoxy-hept-2-enaric acids with D-xylo, D-lyxo, L-arabino, L-lyxo- and D-ribo-configuration were synthesized from D-galactose and D-mannose, respectively, and further characterized by their di-O-acetyl and di-O-benz
- Lichtenthaler, Frieder W.,Klotz, Juergen,Nakamura, Katsumi
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p. 3973 - 3986
(2007/10/03)
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- (-)-Daucic Acid: Revision of Configuration, Synthesis, and Biosynthetic Implications
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The synthesis of dihydropyrans with the D-xylo (1), D-ribo, L-arabino, and D-lyxo (2) configuration by one-carbon-atom homologation of D-mannose or D-galactose, terminal oxidation, and directed β elimination revealed (-)-daucic acid isolated from carrots
- Lichtenthaler, Frieder W.,Nakamura, Katsumi,Klotz, Juergen
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p. 5838 - 5843
(2007/10/03)
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- Efficient Syntheses of β-Cyanosugars Using Glycosyl Iodides Derived from Per-O-silylated Mono- and Disaccharides
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Reported herein is a general method for the efficient syntheses of a variety of β-cyano glycosides through the activation of per-O-trimethylsilyl glycosides with TMSI to form α-glycosyl iodides, which undergo SN2-type displacement when treated with tetrabutylammonium cyanide. The cyanoglycosides were reduced under mild conditions using NaBH4 in the presence of catalytic CoCl2(H2O)6 in THF/H2O to give the corresponding aminomethyl glycosides.
- Bhat, Abhijit S.,Gervay-Hague, Jacquelyn
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p. 2081 - 2084
(2007/10/03)
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- Efficient stereocontrolled synthesis of C-glycosides using glycosyl donors substituted by propane 1,3-diyl phosphate as the leaving group
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α- and β-Glycosyl cyanides, per-O-acetyl-1,2-O-1-cyanoethylidenes and C-allyl glycopyranosides were efficiently prepared by treatment of 2,3,4-tri-O-acetyl-α,β-L-rhamno-, L-fuco- and 2,3,4,6-tetra-O-acetyl-α,β-D-galactopyranosyl propane-1,3-diyl phosphate
- Singh, Gurdial,Vankayalapati, Hariprasad
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p. 1727 - 1735
(2007/10/03)
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- The cyanation reaction of O-acetylated S-glycosyl phosphorothioates.
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The reaction of alpha- and beta-1-S-phosphorothioates of per-O-acetylated monosaccharides (galactose, xylose, glucose) with trimethylsilyl cyanide in the presence of boron trifluoride etherate has been investigated. It has been established that in dichlor
- Kudelska
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p. 687 - 691
(2007/10/03)
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- Behaviour of the primary nitro group under denitration conditions
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Treatment of per-O-acetylated or acetalated glycosylnitromethanes derived from the common hexoses and pentoses with tributyltin hydride and a catalytic amount of a radical initiator [1,1′-azobis(cyclohexanecarbonitrile)] in refluxing benzene easily afforded the corresponding glycosylmethanal oximes in 84-97% yields. Per-O-acetylated C-β-glycopyranosylmethanal oximes were employed for synthesis of versatile C-β-glycopyranosyl cyanides of the β-D-gluco, β-D-manno, β-D-galacto, β-D-xylo, and β-L-rhamno configurations.
- Pham-Huu, Duy-Phong,Petrusova, Maria,BeMiller, James N.,Petrus, Ladislav
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- Preparation of 2,6-Anhydro-3-deoxyhept-(or hex-)2-enononitriles (1-Cyanoglycals) from 1-Bromo-D-glycosyl Cyanides with Zinc under Aprotic Conditions
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Acetylated 1-bromo-D-glycosyl cyanides 1 - 5 react with zinc dust in acetic acid, acetic acid/water, or 2-propanol to give mixtures of acetylated 1-cyanoglycals 6-9 and anomeric pairs of glycosyl cyanides 10-14.Reaction of 1-5 in refluxing benzene in the presence of one equivalent of triethylamine or especially pyridine predominantly leads to the formation of 1-cyanoglycals.
- Somsak, Laszlo,Bajza, Istvan,Batta, Gyula
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p. 1265 - 1268
(2007/10/02)
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- EIN NEUER EFFIZIENTER WEG ZUR DARSTELLUNG VON GLYCOPYRANOSYLCYANIDEN (2,6-ANHYDROALDONONITRILES) OHNE NACHBARGRUPPENBETEILIGUNG. REDUKTION VON 2,6-ANHYDRO-1-DESOXY-1-NITROALDITOLEN MIT PHOSPHORTRICHLORID
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D-Glucose, D-mannose, and D-galactose gave in two steps the corresponding per-O-acetyl-2,6-anhydro-1-deoxy-1-nitroheptitols.Treatment with phosphorus trichloride in pyridine gave directly the corrresponding 3,4,5,7-tetra-O-acetyl-2,6-anhydroheptononitriles ("glycopyranosyl cyanides").The same treatment was applied to the 3,4,5-tri-O-acetyl-2,6-anhydro-1-deoxy-1-nitrohexitols, prepared from D-xylose, D-lyxose, L-aradinose, and D-ribose, and led to the corresponding 3,4,5-tri-O-acetyl-2,6-anhydrohexononitriles in yields ranging from 65 to 80percent.No anomerization was observed, thus allowing the preparation in high yields, of cyanides having even the 1,2-cis configuration.The anhydronitriles were compared with other known examples of this class of compounds and conformational equilibria in solution determined by 1H-n.m.r. spectroscopy.A significant anomeric effect of the cyano group is doubtful.Instead, a stabilizing effect by the 1,3-diaxial arrangement of a cyano group and an acetoxy substituent seems to be present.
- Koell, Peter,Foertsch, Armin
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p. 301 - 316
(2007/10/02)
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- PREPARATION OF 1,2-CIS-GLYCOSYL CYANIDES BY THE STEREOSELECTIVE REDUCTION OF ACETYLATED 1-BROMO-D-GLYCOSYL CYANIDES
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Reductive dehalogenation of acetylated 1-bromo-D-glycosyl cyanides with tri-n-butyltin hydride favours the formation of 1,2-trans-glycosyl cyanides, while reactions with zinc-acetic acid, zinc-isopropanol, and sodium borohydride give 1,2-cis-glycosyl cyanides as the major product.
- Somsak, Laszlo,Batta, Gyula,Farkas, Istvan
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p. 5877 - 5880
(2007/10/02)
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- Synthesis and characterization of some anomeric pairs of per-O-acetylated aldohexopyranosyl cyanides (per-O-acetylated 2,6-anhydroheptononitriles). On the reaction of per-O-acetylaldohexopyranosyl bromides with mercuric cyanide in nitromethane.
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The synthesis and characterization of the anomeric pairs of the per-O-acetylaldohexopyranosyl cyanides of D-galactose, L-fucose, D-glucose, and D-mannose, as well as of 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl cyanide, are described. Cyanation of the readily available, per-O-acetylaldohexopyranosyl bromides with mercuric cyanide in nitromethane, and subsequent purification, gave the corresponding, crystalline glycosyl cyanides with a high degree of 1,2-trans stereoselectivity. Thus, per-O-acetylated aldohexopyranosyl cyanides of the 1,2-trans configuration were obtained in yields ranging from 20 to 79%, whereas the corresponding 1,2-cis anomers were obtained in yields of less than or equal to 8.4%, the ratios of the 1,2-trans:1,2-cis anomers so prepared being greater than or equal to 8.5:1. The principal by-products of these irreversible, cyanation reactions were the per-O-acetylated 1,2-O-[1-(exo- and endo-cyano)ethylidene]aldohexopyranoses, obtained in yields of up to 40%. The structural assignments of the per-O-acetylaldohexopyranosyl cyanides were unequivocally established by elemental analysis, chemical transformation, vibrational spectroscopy, and 13C- and 1H-nuclear magnetic resonance spectroscopy. Correlations between the physical properties and the anomeric configurations of these C-aldohexopyranosyl compounds are described.
- Myers,Lee
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- Synthesis of Ribosyl and Arabinosyl Cyanides by Reaction of 1-O-Acyl Sugars with Trimethylsilyl Cyanide
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A new procedure is described for the synthesis of glycosyl cyanides by reaction of 1-O-acyl sugars with trimethylsilyl cyanide in a polar aprotic solvent and in the presence of a Lewis acid as catalyst.A variety of ribosyl and arabinosyl cyanides have been made in this way from sugar derivatives having acyl, chloro, or methoxy leaving groups at the anomeric position, furanose or pyranose rings, and acyl or benzyl protecting groups.The 1,2-trans-glycosyl cyanide was formed when the starting sugar had a participating 2-O-acyl substituent.A mixture of cyanide anomers was obtained when the starting sugar was protected with non- participating benzyl groups.
- Heras, Federico G. de las,Fernandez-Resa, Piedad
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p. 903 - 908
(2007/10/02)
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- Syntheses of derivatives of lacto-N-biose. I. 4,6-Di-O-acetyl-3-O-(tetra-O-acetyl-β-D-galactopyranosyl)-2-deoxy-2-phthalimido-α,β-D-glucopyranosyl chloride
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Procedures are reported for the synthesis of 4,6-di-O-acetyl-3-O-(tetra-O-acetyl-β-D-galactopyranosyl)-2-deoxy-2-phthalimido-α,β-D-glucopyranosyl chloride, a reagent useful for the reliable introduction of β-D-Galp-(1->3)-β-D-GlcNAcp units (lacto-N-biose
- Lemieux, R. U.,Abbas, S. Z.,Chung, B. Y.
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