Glucopyranosyl Bromide Research Articles

The first synthesis of peracetyl glycosyl aurone derivatives and aurone glucosides

Aurones, a sub-class of the flavonoids with proven therapeutic importance, also exist in variously glycosylated forms. Although a large number of glycosylated aurone derivatives have been isolated from plant sources, no syntheses have been reported yet. Inspired from this gap, here we report the first synthesis of peracetylated glycosyl derivatives of synthetic aurones. The direct O-glycosylation was achieved by reacting 6-hydroxy aurones with 2, 3, 4, 6-tetra-O-acetyl-α-D glucopyranosyl bromide in the presence of a phase transfer catalyst tetrabutylammonium bromide (TBAB). The successful synthesis of aurone glycosides (33 examples) in 60–92% yield will benefit the synthesis of combinatorial libraries of glycosylated aurones for their biological study and comparison with non-glycosylated aurones.

ChemInform Abstract: An Efficient Total Synthesis of Resokaempferol 3‐O‐β‐D‐Glucoside.

AbstractThe synthesis of title compound (VI) from the inexpensive starting material (I) is achieved via an efficient glycosylation for the reaction of compound (III) with the glucopyranosyl bromide (IV).

Synthesis of 1,3-Dithiole-2-thione-4,5-dithiolate-Carbohydrate Conjugate

Bis(tetraethylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato) zincate (5), and 4,5-bis(cyanoethylthio)-1,3- dithiole-2-thione (6) were reacted with 6-deoxy-6-iodo-glucopyranose (2) and glucopyranosyl bromide (3) to synthesize DMIT-carbohydrate conjugates. Keywords: Bis(tetraethylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato) zincate, 4,5-Bis(cyanoethylthio)-1, 3-dithiole-2-thione, 1,3-Dithiole-2-thione-4, 5-dithiolate-carbohydrate conjugates

Synthesis of Some Functionalized 3-(4-Thioxo-3,4-dihydroquinazolin-2-YL) Acrylic Acid of Pharmaceutical Interest

3-(4-Thioxo-3,4-dihydroquinazolin-2-yl)acrylic acid 1 proved to be a convenient precursor for the synthesis of novel polyfunctional quinazoline derivatives of pharmaceutical interest via its treatment with some π-deficient compounds such as phenyl isocyanate and phenyl isothiocyanate. Also, S- and N-glucosidation of quinazoline has been achieved by treatment of 1 with glucopyranosyl bromide in alkaline medium. The behavior of 1 toward acrylonitrile (under Michael reaction condition), paraformaldehyde in the presence of secondary amines (under Mannich reaction condition) and sodium azide were investigated. Moreover, the peptidyl derivatives of quinazoline have been synthesized by condensation of 1 with α-amino acids via different routes. Some of the newly synthesized products were tested for their antimicrobial activities. The structure assignments are based on the analytical and spectroscopic results.

Selective 3‐O‐ and/or 6‐O‐Glycosidation of Unprotected O‐ and S‐Glycosides Promoted by an Intramolecularly Coordinated Arylboronic Compound.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Selective 3-O- and/or 6-O-Glycosidation of Unprotected O- and S-Glycosides Promoted by an Intramolecularly Coordinated Arylboronic Compound

Abstract Arylboronic compound 1 that has intramolecular coordination promotes highly regioselective 3-O- and/or 6-O-glucosidation and -galactosidation of methyl fucopyanoside, methyl galactopyranoside, methyl mannopyranoside, p-methylphenyl 1-thiogalactopyranoside, and p-methylphenyl 1-thiomannopyranoside with peracetylated glucopyranosyl bromide or galactopyranosyl bromide as a glycosyl donor in the presence of Ag2CO3, Et4NI, and molecular sieves 4A in THF. Glycosyl acceptors and promoter 1 form cyclic boronates at cis-vicinal diol (3,4-diol or 2,3-diol) and/or 4,6-diol moieties with concomitant activation of the less hindered 3-O (equatorial) and/or 6-O (primary) nucleophiles via intramolecular O → B coordination. This reaction provides a novel method of simultaneous one-pot 3,6-O-double glycosidation (glucosidation and galactosidation) to give trisaccharides. However, attempted mannosidation with peracetylated mannopyranosyl bromide only gives rise to orthoesters.

Synthesis and structural studies of anomeric 2,3,4,6-tetra- O-acetyl-5-thio- d-glucopyranosyl azides

Two methods are presented for the preparation of the α and β anomers of 2,3,4,6-tetra- O-acetyl-5-thio- d-glucopyranosyl azide. These methods are comparable in yield, but the one that converts a glucopyranosyl bromide into the azide is preferable because of easier purification. After chromatographic separation, the α and β anomers were analysed by NMR spectroscopy. The crystal and molecular structure of the β anomer was determined by X-ray diffraction. It crystallises in space group P2 1 [ a=11.729(3), b=7.305(3), c=11.363(3)Å, β=107.63(5)°, Z=2]. The hexopyranose ring of the β anomer assumes a 4 C 1 conformation and the orientation of the azido group is compatible with the requirements of the exo-anomeric effect. This geometry is compared to that of other similar structures.

The Synthesis of Some Seleno- and Telluro-β-D-glucopyranosides

Several new seleno- and telluro-β-D-glucopyranosides have been prepared by treatment of protected α-D- glucopyranosyl bromides with the appropriate dialkyl or diaryl dichalcogenide and sodium borohydride in ethanol.

Synthesis of sulfur-linked analogues of nigerose, laminarabiose, laminaratriose, gentiobiose, gentiotriose, and laminaran trisaccharide Y

Sulfur-linked analogues of 3-O-α- d- glucopyranosyl- d- glucose (nigerose), 3-O-β- d- glucopyranosyl- d- glucose (laminarabiose), 6-O-β- d- glucopyranosyl- d- glucose (gentiobiose), O-β- d- glucopyranosyl-(1 → 3)-O-β- d- glucopyranosyl-(1 → 3)- d- glucose (laminaratriose), O-β- d- glucopyranosyl-(1 → 6)-O-β- d- glucopyranosyl-(1 → 6)- d- glucose (gentiotriose) and 3,6- di-O-β- d- glucopyranosyl- d- glucose (laminaran trisaccharide Y), namely, respectively, 3-thionigerose ( 6), 3-thiolaminarabiose ( 11), 6-thiogentiobiose ( 21), 3 I,3 II-dithiolaminaratriose ( 16), 6 I,6 II-dithiogentiotriose ( 29) and 3 I,6 I-dithiolaminaran trisaccharide Y ( 37) have been conveniently prepared by S N2 reactions of the corresponding anomer of d-glucopyranose 1-thiolate with suitably activated monosaccharide derivatives in N, N-dimethylformamide (for 6 and 21) or in tetrahydrofuran in the presence of a crown ether (for 11). A sequence involving the reaction of non-anomeric thiolates with 2,3,4,6- tetra-O- acetyl-α- d- glucopyranosyl bromide was alternatively used for the preparation of 11 and 21 but proved less satisfactory. The preparation of thiotrisaccharides 16, 29, and 37 involved a mixed approach.

Synthesis and characterization of an insulin-mimetic disaccharide

A glucosaminyl-inositol-1,2-cyclic phosphate, 1, has been synthesized and evaluated for selected insulin-mimetic properties. The compound was designed to resemble structurally the recently reported inositol glycans which are believed to be insulin second messengers. The synthesis utilized a Koenigs-Knorr glycosylation of optically pure 1-camphanyl-2,3:4,5-di-0-cyclohexylidene-myo-inositol with 2-azido-3,4,6-tri-0-benzyl-2-deoxy-α-D- glucopyranosyl bromide followed by phosphitylation by the phosphoramidite method, oxidation, and carbodiimide cyclisation

ChemInform Abstract: The Use of N‐Alkoxycarbonyl Derivatives of 2‐Amino‐2‐deoxy‐D‐glucose as Donors in Glycosylation Reactions.

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Synthesis of 3′-deoxy-3′-fluorokanamycin A and 3′,4′-dideoxy-3′-fluorokanamycin A

3′-Deoxy-3′-fluorokanamycin A ( 14) has been prepared by condensation of 6-azido-2,4-di- O-benzyl-3,6-dideoxy-3-fluoro-α- d- glucopyranosyl bromide ( 8) and 6- O-(2- O-acetyl-4,6- O-cyclohexylidene-3-deoxy-3-tosylamino-α- d-glucopyranosyl)-2-deoxy-1,3-di- N- tosylstreptamine ( 10). Compound 8 was obtained from 3-deoxy-3-fluoro-1,2:5,6-di- O-isopropylidene- d-glucofuranose in seven steps. 3′,4′-Dideoxy-3′-fluorokanamycin A ( 22) has been prepared from 12 through selective 4′-chlorodeoxygenation, a key reaction. Both 14 and 22 were more active than 3′-deoxykanamycin A against both sensitive and resistant bacteria.

Preparation of some fully chloroacetylated glycopyranosyl bromides: Useful intermediates for the synthesis of base‐ and hydrogenolysis‐sensitive glycosides

AbstractChloroacetylation of alkyl glycopyranosides of β‐D‐galactose, β‐D‐glucose and α‐D‐mannose as well as of free D‐glucose, D‐galactose, D‐mannose and D‐xylose, using chloroacetic anhydride as acylating reagent, gave the corresponding fully chloroacetylated pyranose derivatives in excellent yields. From D‐glucose, 1,2,3,6‐tetra‐O‐chloroacetyl‐α‐D‐glucopyranose (9) was also obtained. Subsequent treatment of the fully chloroacetylated α‐D‐glycopyranoses 3, 8, 13 and 15 of galactose, glucose, mannose, and xylose, respectively, with HBr resulted in 2,3,4,6‐tetra‐O‐chloroacetyl‐α‐D‐galactopyranosyl bromide (4, 98%), ‐glucopyranosyl bromide (10, 92%), ‐mannopyranosyl bromide (14, 72%) and 2,3,4‐tri‐O‐chloroacetyl‐α‐D‐xylopyranosyl bromide (16, 68%). 10 reacted with D‐pantholactone (17) and silver trifluoromethanesulfonate under acidic conditions to give the corresponding α‐linked (18, 45%) and β‐linked (20, 38%) glucopyranosides. Under basic conditions the corresponding ortho ester product 21 was formed (92%) which upon treatment with BF3 gave the glucosides 18 and 20. Silver silicate as the catalyst gave only traces of 18. Thus, 20 was isolated in 80% yield. Reaction of 10 with silver crotonate and silver laurate gave 1‐O‐crotonoyl‐ (22) and 1‐O‐lauroyl‐2,3,4,6‐tetra‐O‐chloroacetyl‐β‐D‐glucopyranose (24), respectively. 18 and 22 were dechloroacetylated with thiourea, affording the corresponding deblocked glucose derivatives 19 and 23, respectively.

The use of N-alkoxycarbonyl derivatives of 2-amino-2-deoxy- d-glucose as donors in glycosylation reactions

1,3,4,6-Tetra- O-acetyl-2-alkoxycarbonylamino-2-deoxy-β- d-glucopyranoses and 3,4,6-tri- O-acetyl-2-alkoxycarbonylamino-2-deoxy- a- d-glucopyranosyl bromides have been used as donors in glycosylation reactions with model alcohols. β-Glycosides were obtained in good yields and with a high degree of 1,2- trans stereoselectivity. An oxazolidinone was formed as the main product from the reaction of some of the glucopyranosyl bromides with alcohols of low reactivity, but the formation of all products could be interpreted by a strong participation of the alkoxycarbonylamino group.

Utilisation de dérivés 2-alkoxycarbonylés dans les réactions de glucosylation. Synthèse stéréosélective d'orthocarbonates

Glucopyranosyl bromides bearing a C-2 alkoxycarbonyl protective group were treated with alcohols under Koenigs-Knorr conditions. Depending on the promotor, the condensations afforded β- d-glucosides, orthocarbonates, or both with a high stereoselectivity. The reaction mechanism implies a participating alkoxydioxocarbenium intermediate, followed by addition of alcohol to give β- d-glucosides and orthocarbonates via two independent pathways.

ChemInform Abstract: A Reexamination of the Synthesis of Paracetamol Glucuronide, the Major Urinary Metabolite of Paracetamol in Man.

AbstractThe title compound (V) can be efficiently prepared starting either from the (tetra‐O‐acetyl glucopyranoside)uronate (I) or (tri‐O‐acetyl glucopyranosyl bromide)‐uronate (III) via the condensation product (IV).

Synthesis of methyl glycoside derivatives of tri- and penta-saccharides related to the antithrombin III-binding sequence of heparin, employing cellobiose as a key starting-material

Two key synthons for the title pentasaccharide derivative, methyl 2- O-benzoyl-3- O-benzyl-α- l-idopyranosyluronate)-(1→4)-6- O-acetyl-2-azido-3- O-benzyl-2-deoxy-β- d-glucopyranoside and O-(methyl 2,3-di- O-benzyl-4- O-chloroacetyl-β- d-glucopyranosyluronate)-(1→4)-3,6-di- O-acetyl-2-azido-2-deoxy-α- d- glucopyranosyl bromide, were prepared from a common starting material, cellobiose. They were coupled to give a tetrasaccharide derivative that underwent O-dechloroacetylation to the corresponding glycosyl acceptor. Its condensation with the known 6- O-acetyl-2-azido-3,4-di- O-benzyl-2-deoxy-α- d-glucopyranosyl bromide afforded a 77% yield of suitably protected pentasaccharide, methyl O-(6- O-acetyl-2-azido-3,4-di- O-benzyl-2-deoxy-α- d-glucopyranosyl)-(1→4)- O-(methyl 2,3-di- O-benzyl-β- d-glucopyranosyluronate)-(1→4)- O-(3,6-di- O-acetyl-2-azido-2-deoxy-α- d-glucopyranosyl)-(1→4)- O-(methyl 2- O-benzoyl-3- O-benzyl-α- l-idopyranosyluronate)-(1→4)-6- O-acetyl-2-azido-3- O-benzyl-2-deoxy-β- d-glucopyranoside. Sequential deprotection and sulfation gave the decasodium salt of methyl O-(2-deoxy-2-sulfamido-6- O-sulfo-α- d-glucopyranosyl)-(1→4)- O-(β- d-glucopyranosyluronic acid)-(1→4)- O-(2-deoxy-2-sulfamido-3,6-di- O-sulfo-α- d-glucopyranosyl)- (1→4)- O-(2- O-sulfo-α- l-idopyranosyluronic acid)-(1→4)-2-deoxy-2-sulfamido-6- O-sulfo-β- d-glucopyranoside ( 3). In a similar way, the trisaccharide derivative, the hexasodium salt of methyl O-(2-deoxy-2-sulfamido-6- O-sulfo-α- d-glucopyranosyl)-(1→4)- O-(β- d-glucopyranosyluronic acid)-(1→4)-2-deoxy-2-sulfamido-3,6-di- O-sulfo-α- d-glucopyranoside ( 4) was synthesized from methyl O-(6- O-acetyl-2-azido-3,4-di- O-benzyl-2-deoxy-α- d-glucopyranosyl)-(1→4)- O-(methyl 2,3-di- O-benzyl-β- d-glucopyranosyluronate)-3,6-di- O-acetyl-2-azido-2-deoxy-α- d-glucopyranoside. The pentasaccharide 3 binds strongly to antithrombin III with an association constant almost equivalent to that of high-affinity heparin, but the trisaccharide 4 appears not to bind.

ChemInform Abstract: Stereoselective Synthesis of α‐D‐Glucopyranosides via 6‐Silyl‐α‐D‐glucopyranosyl Bromides.

AbstractThe anhydroglucopyranose (I) is cleaved with trimethylsilyl bromide to give the glucopyranosyl bromide (II).

ChemInform Abstract: Improved Preparations of Some Per‐O‐Acetylated Aldohexopyranosyl Cyanides.

Abstract 3,4,6-Tri- O -acetyl-1,2- O -[1-( exo -, endo -cyano)ethylidene]-α- d -galacto- ( 1a/b ), -α- d -gluco- ( 2a/b ), and -β- 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-α- d -manno- and -gluco-pyranosyl bromide with mercuric cyanide in nitromethane generates, in the ratio of ∼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-α- and -β- d -galacto, -α- and -β- d -gluco-, -α- d -manno-, and -2-deoxy-2-phthalimido-β- 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-α- and -β- d -mannopyranosyl cyanide (48 and 16% total yield, respectively) and -α- and -β- d -glucopyranosyl cyanide (12 and 39% total yield, respectively) were synthesized by fusion of the corresponding -α- d -glycosyl bromides with mercuric cyanide.

ChemInform Abstract: Synthesis of Some Derivatives of 6‐Amino‐1,5‐anhydro‐6‐deoxy‐D‐glucitol and 2‐Amino‐1,5‐anhydro‐2‐deoxy‐D‐glucitol.

AbstractThe 6‐amino‐6‐deoxy derivative (II) is prepared from 1,5‐anhydro‐D‐glucitol (Ia).