Stereoselective synthesis of triterpene 2-deoxy-α-d-lyxo-hexopyranosides

2-Deoxy-α-d-lyxo-hexopyranosides of 18β-glycyrrhetic acid, its 11-deoxo derivative and allobetulin were synthesized by glycosylation of oleonane-type triterpene alcohols withd-galactal acetate in the presence ofN-iodosuccinimide followed by deiodination and deprotection. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 596–600. March, 1997.     

Stereoselective synthesis of 2-deoxy-α-d-arabino-hexopyranosides of triterpene alcohols

2-Deoxy-2-iodo--d-mannopyranosides of triterpene alcohols of the oleanane series were synthesized inca. 60% yields by glycosylation with readily accessibled-glucal triacetate in the presence ofN-iodosuccinimide as the promotor. Their deiodination by catalytic hydrogenation followed by deacetylation yielded 2-deoxy--d-arabino-hexopyranosides of glycyrrhetic acid derivatives and allobetulin.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2340–2346, September, 1996.     

Reactions of ethyl triphenylphosphoranylideneacetate with fluorinated β-ketoaldehyde derivatives

The reactions of fluorinated β-ketoaldehyde derivatives: β-alkoxyvinyl polyfluoroalkyl ketones 1 and fluorinated β-ketoacetals 2 with ethyl triphenylphosphoranylideneacetate 3 are described. In the case of ketones 1 the result of the reaction is a mixture of products: fluorinated alkoxydienes 5 (Wittig reaction product) and polyfluoroacyl vinyl ylides 7 (Michael addition product). The reaction with fluorinated β-ketoacetals 2 leads to a mixture of E- and Z-isomers of polyfluoroalkyl acrylates 8 and 9, respectively. The influence of the nature of fluorinated substituent and solvent or other factors on the outcome of the reactions are discussed.     

Syntheses of Novel 3-Substituted-2′-deoxy-3-deazauridine Nucleosides

Syntheses of novel 3-ethynyl (8), 3-vinyl (10) and 3-acetoxy (13)-2′-deoxy-3-deazauridine analogs starting from the protected 2′-deoxy-3-deazauridine derivative 4 are described.     

α-n-hydroxyamino acid derivatives

Reactions of organolithium reagents with glyoxylate derived oximes provided a direct route to α-N-hydroxyamino acids. The process required direct attachment of an ionizable group to the glyoxylate carbonyl to prevent competitive reactions. The procedure allowed for direct formation of the α-chiral center of the newly formed α-N-hydroxyamino acid derivative. Introduction of potential chiral auxiliaries on the oxime oxygen resulted in modest diastereoselection. In most instances, use of chiral glyoxylamides also gave low diastereoselectivity.     

Synthesis and Conformational Analysis of 1, 2-Anhydro-3, 4-di-O-benzyl-6-deoxy-α-D-glucopyranose

Abstract

The title 1, 2-anhydro sugar (10) was synthesized from methyl 4, 6-O-benzylidene-α-D-glucopyranoside or from 1, 2-O-ethylidene-α-D-glucopyranose. The key intermediate for the synthesis was 2-O-acetyl-3, 4-di-O-benzyl-6-deoxy-β-D-glucopyranosyl fluoride (8)which was transformed into the target compound by ring closure with potassium tert-butoxide. Calculations by the modified Karplus equation from vicinal coupling constants of 10 suggested that the conformation of 10 was almost an ideal ⁴ H ₅ for the pyranose ring. Conformational analysis for the 1, 2-O-(R)-ethylidene intermediates 17 and 20 revealed that their pyranose ring basically adopted a B₂,₅ conformation.     

Stereoselective Synthesis and Crystal Structure Analysis of N-Naphthyl-2-deoxy-α-D-ribopyranosylamine

A new compound N-naphthyl-2-deoxy-α-D-ribopyranosylamine was synthesized and structurally determined. It crystallizes in the orthorhombic system, space group P212121 with a = 8.361（2）, b = 12.432（3）, c = 12.791（4） A^°, Z= 4, V= 1329.6（6） A^°^3, Dc= 1.295 g/cm^3, F（000） = 552, Cl5H17NO3 and Mr= 259.30. All the active hydrogen atoms are involved in the formation of hydrogen bonds in the molecule.     

Synthesis and reactions of 2-deoxy-β-D-ribofuranosyl derivatives of 3-aryl-4H-pyrrolo[2,3-d]pyrimidin-4-imines

Summary 3-Aryl-7-(2-deoxy--D-erythro-pentofuranosyl)-3,7-dihydro-4H-pyrrolo[2,3-d]-pyrimidin-4-imines (4) as well as 4-arylamino-7-(2-deoxy--D-erythro-pentofuranosyl)-2-methyl-5-phenyl-7H-pyrrolo[2,3-d]pyrimidines (7) have been synthesized by glycosylation of the sodium salt of the corresponding nucleobases with 2-deoxy-3,5-di-O-p-toluyl--D-erythro-pentofuranosyl chloride (2) followed by subsequent deprotection with sodium methoxide in methanol. The deprotected nucleoside4 undergoes aDimroth rearrangement on reflux for 24 h in water to furnish the 4-arylamino nucleoside7.

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Synthese und Reaktionen von 2-Deoxy--D-ribofuranosylderivaten von 3-Aryl-4H-pyrrolo[2,3-d]pyrimidin-4-iminen

Zusammenfassung 3-Aryl-7-(2-deoxy--D-erythro-pentafuranosyl)-3,7-dihydro-4H-pyrrolo[2,3-d]-pyrimidin-4-imine (4) und 4-Arylamino-7-(2-deoxy--D-erythro-pentofuranosyl)-2-methyl-5-phenyl-7H-pyrrolo[2,3,-d]pyrimidine (7) wurden durch Glycosylierung der Natriumsalze der entsprechenden Nucleosidbasen mit 2-Deoxy-3,5-di-O-p-toluyl--D-erythro-pentofuranosylchlorid (2) und anschließende Entfernung der Schutzgruppe mit Natriummethoxid in Methanol hergestellt. Das entschützte Nucleosid4 ergibt bei 24-stündigem Erhitzen in Wasser unter Rückfluß über eineDimroth-Umlagerung das 4-Aminonucleosid7.

     

Stereoselective synthesis of deoxycarbaheptopyranose derivatives: 5a-carba-6-deoxy-α-dl-galacto-heptopyranose and 5a-carba-6-deoxy-α-dl-gulo-heptopyranose

Two new deoxycarbaheptopyranoses, 5a-carba-6-deoxy-α-dl-galacto-heptopyranose and 5a-carba-6-deoxy-α-dl-gulo-heptopyranose were prepared starting from cyclohexa-1,4-diene. The addition of dichloroketene to cyclohexa-1,4-diene followed by the subsequent reductive elimination and Baeyer-Villiger oxidation in turn led to the formation of a bicyclic lactone. Reduction of the lactone moiety followed by acetylation gave a diacetate with cis-configuration. The introduction of additional acetate functionality into the molecule was achieved by singlet oxygen ene-reaction. The formed hydroperoxide was reduced and then acetylated. The triacetate was further functionalized either by direct cis-hydroxylation using OsO₄ or by epoxidation followed by a ring-opening reaction to give the title heptopyranose derivatives. One of the synthesized molecules, galacto-heptopyranose exhibited enzyme specific inhibition against α-glycosidase. On the other hand, they did not show any inhibition for α-amylase. However, both compounds, gulo-heptopyranose and galacto-heptopyranose increased the activity of α-amylase.     

Efficient route to orthogonally protected precursors of 2-acylamino-2-deoxy-3-O-substituted-β-d-glucopyranose derivatives and use thereof

An efficient route to two 3-O-acyl-2-deoxy-4,6-O-isopropylidene-2-trichloroacetamido-d-glucopyranosyl trichloroacetimidate donors is reported. As demonstrated for the 3-O-acetyl derivative, these building blocks are exquisite β-d-glucosamine donors when reacted either with simple alcohols or with complex oligosaccharides. Besides, their protection pattern is compatible with selective deprotection and subsequent chain elongation at O-3 of the newly incorporated glucosamine residue.     

Two new 3-oxo-α-ionol glucosides from Urtica laetevirens Maxim

Two new 3-oxo-α-ionol glucoside isomers, (6R,9R)-3-oxo-α-ionol-9-O-β-D-glucopyranosyl (1?→?2)-β-D-glucopyranoside (1) and (6S,9R)-3-oxo-α-ionol-9-O-β-D-glucopyranosyl (1?→?2)-β-D-glucopyranoside (2) were isolated from the aerial parts of Urtica laetevirens Maxim. Their structures, including stereochemistry, were established by spectral analyses (HR-ESI-MS, NMR and CD). Also, 3-oxo-α-ionol glucosides were isolated from Urtica species for the first time.     

Allylic strain as a stereocontrol element in the hydrogenation of 3-hydroxymethyl-cyclohex-3-en-1,2,5-triol derivatives. Synthesis of the carbasugar pseudo-2-deoxy-α-d-glucopyranose

By adaptation of a literature method developed in the glucose series and standard protecting group manipulations a 2-deoxy-d-glucose derivative is converted to a series of 1R,2R,5R-3-hydroxymethyl-cyclohexen-1,2,5-triol derivatives whose reduction to the corresponding diastereomeric d-gluco and l-ido-2-deoxy carbasugars is studied. When the hydroxymethyl group is tied up in a cyclic isopropylidene acetal with the adjacent 6-hydroxy group the cis-fused products with the ido-configuration are formed preferentially whereas protection of the hydroxymethyl group as a methoxymethyl ether results in the formation of the d-gluco isomer on hydrogenation over Raney nickel. This result is rationalized in terms of the minimization of allylic strain in the course of the reduction, enables the preparation of the carbasugar pseudo-2-deoxy-α-d-glucopyranose, and suggests that the conformation of the side chain is an important control element in the chemistry of the pseudosugars as it is in the sugars themselves.     

Synthesis of the 3-0, 4-0 and 6-0 Sulfates of Methyl 2-amino-2-deoxy-α-D-Glucopyranoside

Abstract

Starting with methyl 2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (1), the isomeric methyl 2-amino-2-deoxy-α-D-glucopyranoside 3-, 4-, and 6-sulfates have each been prepared by sulfation of suitably blocked intermediates. Tritylation and acetylation of 1 followed by detritylation gave methyl 3,4-di-0-acetyl-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (3), having a free 6-hydroxyl group. Base catalyzed 0–4→0–6 acetyl migration provided the corresponding 3,6 di-O-acetyl derivative (4) posessing a free 4-hydroxyl group. Preparation of methyl 4,6-0-benzylidene-2-(benzyloxycarbonyl)amino-2-deoxy-α-D-glucopyranoside (9) provided the intermediate bearing a free 3-hydroxyl group. 0-sulfation of 3, 4, and 9 was effected with the pyridine sulfur trioxide complex in dry pyridine.     

Stereoselective synthesis of s-(2-deoxy-α-D-glycosyl)- phosphorodithioates1 and of their (2R)-2-deoxy-2-deuterio- analogues. Novel route to C-2 d

Addition of 0,0-dialkylphosphorodithioic acids to fully protected 1,2-unsaturated hexo- and pentopyranoses gives S-(2-deoxy-glycosyl)-phosphorodithioates in quantitative yield and high stereoselectivity with respect to the α-isomer. The stereochemistry of this reaction is “cis” as demonstrated by the addition of deuterated 0,0-dialkylphosphorodithioic acids to 3,4,6-tri-O-acetyl-D-glucal which gives exclusively the α-dithiophosphates of (2R)-2-deoxy-2-deuterio-D-arabinohexopyranose. This result provides an efficient and fully stereoselective method of labeling of the deoxy function in 2-deoxy monosaccharides and their glycosylic derivatives.     

Aryl-ONN-azoxy-α,α-dinitroalkanes and some of their derivatives

Previously unknownN-dinitroalkyl-NNO-azoxybenzenes have been prepared (by nitration ofN-(-hydroximino) alkyl-NNO-azoxybenzenes) and transformed to some derivatives.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1972–1975, November, 1994     

Stereoselective synthesis of fluorinated β-aminoacids from ethyl trans-N-benzyl-3-trifluoromethylaziridine-2-carboxylate

trans-N-Benzyl-3-trifluoromethyl-2-ethoxycarbonylaziridine 2a, easily obtainable in enantiopure forms by CAL-catalysed enzymatic resolution, allowed the regio- and stereoselective synthesis of chiral fluorinated anti-α-functionalised-β-aminoacids, such as trifluoroisoserinates or trifluoro-β-alanine, and trans-3-halo- or 3-hydroxy-β-lactams. Starting from the enantiomerically pure methyl analogue of the title compound, 2c, pure enantiomers of trifluoroisoserine can be obtained in high overall chemical yield. Absolute configurations of optically active β-aminoacids were determined by chemical correlation.     

Chiral Phosphine Ligands Derived fro m Sugars .14 . Crystal Structure of Diphenyl( m ethyl4’,6’-O-benzylidene-3’-deoxy-α- D-altropyranoside-3-)phosphine Oxide

１　ＩＮＴＲＯＤＵＣＴＩＯＮＣｈｉｒａｌｐｈｏｓｐｈｉｎｅｓａｒｅｕｓｅｆｕｌｌｉｇａｎｄｓｉｎｅｎａｎｔｉｏｓｅｌｅｃｔｉｖｅｃａｔａｌｙｓｉｓｗｉｔｈｔｒａｎｓｉｔｉｏｎｍｅｔａｌｃｏｍｐｌｅｘｅｓ〔１〕，ｓｏｍｅｏｆｔｈｅｍｄｅｒｉｖｅｄｆｒｏｍｓｕｇａｒｓａｒｅａｌｓｏｏｆｐｏｔｅｎｔｉａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｂｉｐｈａｓｉｃｃａｔａｌｙｓｉｓ〔２〕ａｎｄｍｅｄｉｃｉｎｅ〔３〕．Ｂｙｔｈｅｎｕｃｌｅｏｐｈｉｌｉｃｒｅｐｌａｃｅｍｅｎｔｒｅａｃｔｉｏｎ，ｉｔｉｓｄｉｆｆｉｃｕｌ…     

Synthesis of 2β, 3β, 14α-trihydroxy-Δ4,7-6-ketosteroids and their derivatives

A scheme using -sitosterol as an example for synthesizing 2, 3, 14-trihydroxy-^4,7-6-ketosteroids and their derivatives from 3-hydroxy-⁵-steroids was developed.Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, 220141, Belarus, Minsk, ul, akad. Kuprevicha, 5/2. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 244–248, May–June, 2000.