α‐d‐Glucofuranose and α‐d‐allofuranose diacetonides and silyl ether of α‐d‐glucofuranose diacetonide in dithiophosphorylation reactions

α‐d ‐Glucofuranose and α‐d ‐allofuranose diacetonides react with 2,4‐diorganyl 1,3,2,4‐dithiadiphosphetane‐2,4‐disulfides to form optically active dithiophosphonates in 78–81% yields, which are transformed into the corresponding ammonium salts in 90–97% yields by the treatment of n‐hexadecylamine. The S‐silyldithiophosphonate was prepared in 93% yield by the reaction of 2,4‐bis(butoxyphenyl) 1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide with silyl ether of α‐d ‐glucofuranose diacetonide. One of the salts obtained possesses antibacterial activity against Staphylococcus aureus ATCC 6538‐P.     

Thionation of N‐(ω‐Halogenoalkyl)‐Substituted Amides with Lawesson's Reagent: Facile Synthesis of 4,5‐Dihydro‐1,3‐thiazoles and 5,6‐Dihydro‐4H‐1,3‐thiazines

The thionation and cyclization of N‐(ω‐halogenoalkyl)‐substituted amides (and related compounds) with Lawesson's reagent (LR=2,4‐bis(4‐methoxyphenyl)‐1,3,2,4‐dithiadiphosphetane 2,4‐disulfide) has been investigated. Treatment of the amides 1 with LR gave the corresponding thioamides 2 in moderate to good yields (Table). The latter, upon treatment with base, afforded, either in a separate step or in a one‐pot procedure, the cyclized title compounds, i.e., the 4,5‐dihydro‐1,3‐thiazoles 3 or the corresponding 5‐6‐dihydro‐4H‐thiazines 4 via dehydrohalogenation.     

Synthesis of 3′‐Thioamido‐Modified 3′‐Deoxythymidine 5′‐Triphosphates by Regioselective Thionation and Their Use as Chain Terminators in DNA Sequencing

The thioamide derivatives 3′‐deoxy‐5′‐O‐(4,4′‐dimethoxytrityl)‐3′‐[(2‐methyl‐1‐thioxopropyl)amino]thymidine ( 4a ) and 3′‐deoxy‐5′‐O‐(4,4′‐dimethoxytrityl)‐3′‐{{6‐{[(9H‐(fluoren‐9‐ylmethoxy)carbonyl]amino}‐1‐thioxohexyl}amino}thymidine ( 4b ) were synthesized by regioselective thionation of the corresponding amides 3a and 3b with 2,4‐bis(4‐methoxyphenyl)‐1,3,2,4‐dithiadiphosphetane 2,4‐disulfide (Lawesson's reagent). The addition of exact amounts of pyridine to the reaction mixture proved to be essential for an efficient transformation. The thioamides were converted into the corresponding 5′‐triphosphates 6a and 6b . Compound 6a was chosen for DNA sequencing experiments, and 6b was further labelled with fluorescein (→ 8 ).     

One‐Pot Approach to Organo‐Phosphorus–Chalcogen Macrocycles Incorporating Double OP(S)SCn or OP(Se)SeCn Scaffolds: A Synthetic and Structural Study

The development of new methodology for the preparation of functional macrocycles with practical applications is an important research area in macromolecular science. In this study, we report a new one‐pot route for the synthesis of a series of macro‐heterocycles by incorporating two phosphorus atoms and two chalcogen atoms and two oxygen atoms (double OP(S)SC_n or OP(Se)SeC_n scaffolds). The three‐component condensation reactions of 2,4‐diferrocenyl‐1,3,2,4‐diathiadiphosphetane 2,4‐disulfide ( FcLR , a ferrocene analogue of Lawesson's reagent) or 2,4‐bis(4‐methoxyphenyl)‐1,3,2,4‐dithiadiphosphetane 2,4‐disulfide ( LR , Lawesson's reagent), or 2,4‐diphenyl‐1,3,2,4‐diselenadiphosphetane 2,4‐diselenide ( WR , Woollins’ reagent), disodium alkenyl‐diols, and dihalogenated alkanes are performed, giving rise to soluble and air or moisture‐stable macrocycles in good‐to‐excellent yields (up to 92 %). This is the first systemically preparative and readily scalable example of one‐pot ring opening/ring extending reaction of three‐components to prepare phosphorus–chalcogen containing macrocycles. We also provide a systematic crystallographic study.     

New Route for the Synthesis of Hetaryl‐1,5‐benzodiazepines: Part 2

1,2,4‐Triazin‐3‐ylthio‐, 1,2,4‐triazepin‐3‐ylthio‐, 1,2,4‐triazol‐3‐ylthio‐, and 1,2,4,3‐triazaphosphol‐5‐ylthio‐1,5‐benzodiazepines 4 – 20 were prepared via the reaction of 2‐oxo‐4‐phenyl‐2,3‐dihydro‐1H‐1,5‐benzodiazepin‐3‐ylhydrazonothiocarbamate ( 2 ) with halocompounds, dicarbonyl compounds, enaminones, 4‐chlorobenzaldehyde, 4‐chlorobenzylidenemalononitriles, N,N‐dimethylformamide dimethylacetal, carbon disulfide, and 2,4‐bis(4‐methoxyphenyl)‐1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide (Lawesson's reagent).     

Thionation of ω‐Acylamino Ketones with Lawesson's Reagent: Convenient Synthesis of 1,3‐Thiazoles and 4H‐1,3‐Thiazines

The reaction of ω‐acylamino ketones with Lawesson's reagent (=2,4‐bis(4‐methoxyphenyl)‐1,3,2,4‐dithiadiphosphetane 2,4‐disulfide; LR ) is described. Treatment of 2‐acylamino ketones 1 (n=0) with LR gave 1,3‐thiazole derivatives 3 in good yields (Scheme 1 and Table 1). The 4H‐1,3‐thiazines 4 were obtained as main products by treatment of 3‐acylamino ketones 2 (n=1) with an equimolar amount of LR , while mainly the corresponding 3‐(thioacyl)amino ketones 5 were isolated when 0.5 equiv. of LR was used. The 3‐acylamino esters 7 also reacted with LR to give the corresponding 3‐(thioacyl)amino esters 8 (Scheme 3 and Table 2).     

Synthesis,molecular and crystal structure,and properties of 10‐propylthio‐5,10‐dihydrophenarsazine

10‐Propylthio‐5,10‐dihydrophenarsazine 2 was obtained by the reaction of 10‐chloro‐5,10‐dihydrophenarsazine 1 with propanethiol in the presence of triethylamine under mild conditions. The structure of 2 was established by X‐ray single crystal diffraction. The reaction of 2 with 2,4‐bis(ethylthio)‐1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide 3 at room temperature affords a novel route to S‐10(5,10‐dihydrophenarsazine) S′‐ethyl‐S″‐propyltetrathiophosphate 4 . © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:287–291, 2000     

Studies on organophosphorus compounds: Synthesis and reactions of [1,2,4,3]triaza‐phospholo[4,5‐a]quinoxaline derivative

2,4‐Bis‐(4‐methoxyphenyl)‐1,3,2,4‐dithiadiphosphetane‐2,4‐disulfide (Lawesson's reagent) ( 1 ) reacted with 2‐hydrazino‐3‐methyl‐quinoxaline ( 2 ) to give [1,2,4,3]‐triazaphospholo[4,5‐a]quinoxaline derivative 3 . The Mannich reaction using different amines on compound 3 gave Mannich bases 4a–d . Also, compound 3 reacted with formaldehyde to give the corresponding 2‐hydroxymethyl derivative 5 , which upon reaction with thionyl chloride gave the corresponding chloromethyl derivative 6 . Treatment of compound 6 with some thiols yielded the corresponding sulfides 7a–d . Acylation of compound 3 gave acylated compounds 8a,b . Compound 9 , which was prepared through the reaction of compound 3 with ethyl cyanoacetate, was investigated as a starting material for the synthesis of some new heterocyclic systems 10–13 . Also, reaction of compound 9 with carbon disulfide and 2 equivalents of methyl iodide in a one‐pot reaction yielded the corresponding ketene‐S,S‐acetal 14 , which in turn reacted with bidentates to give some new heterocycles 15–17 . © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:520–529, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20473     

catena‐Poly[[[μ‐1,3‐bis(diphenylphosphanyl)propane‐κ2P:P′][O‐ethyl (4‐methoxyphenyl)phosphonodithioato‐κ2S,S′]silver(I)] chloroform monosolvate]

Reaction of a mixture of AgOAc, Lawesson's reagent [2,4‐bis(4‐methoxyphenyl)‐1,3‐dithiadiphosphetane‐2,4‐disulfide] and 1,3‐bis(diphenylphosphanyl)propane (dppp) under ultrasonic treatment gave the title compound, {[Ag(C₉H₁₂O₂PS₂)(C₂₇H₂₆P₂)]·CHCl₃}_n, a novel one‐dimensional chain based on the in situ‐generated bipodal ligand [ArP(OEt)S₂]⁻ (Ar = 4‐methoxyphenyl). The compound consists of bidentate bridging 1,3‐bis(diphenylphosphanyl)propane (dppp) and in situ‐generated bidentate chelating [ArP(OEt)S₂]⁻ ligands. The dppp ligand links the [Ag{ArP(OEt)S₂}] subunit to form an achiral one‐dimensional infinite chain. These achiral chains are packed into chiral crystals by virtue of van der Waals interactions. No π–π interactions are observed in the crystal structure.     

Stereoselective Synthesis of 8‐Oxabicyclo[3.2.1]octane‐2,3,4,6,7‐pentols and Total Asymmetric Synthesis of 2,6‐Anhydrohepturonic Acid Derivatives and of β‐C‐manno‐Pyranosides Suitable for the Construction of (1→3)‐C,C‐Linked Trisaccharides

Enantiomerically pure (+)‐(1S,4S,5S,6S)‐6‐endo‐(benzyloxy)‐5‐exo‐{[(tert‐butyl)dimethylsilyl]oxy}‐7‐oxabicyclo[2.2.1]heptan‐2‐one ((+)‐ 5 ) and its enantiomer (−)‐ 5 , obtained readily from the Diels‐Alder addition of furan to 1‐cyanovinyl acetate, can be converted with high stereoselectivity into 8‐oxabicyclo[3.2.1]octane‐2,3,4,6,7‐pentol derivatives (see 23 – 28 in Scheme 2). A precursor of them, (1R,2S,4R,5S,6S,7R,8R)‐7‐endo‐(benzyloxy)‐8‐exo‐hydroxy‐3,9‐dioxatricyclo[4.2.1.0^2,4]non‐5‐endo‐yl benzoate ((−)‐ 19 ), is transformed into (1R,2R,5S, 6S,7R,8S)‐6‐exo,8‐endo‐bis(acetyloxy)‐2‐endo‐(benzyloxy)‐4‐oxo‐3,9‐dioxabicyclo[3.3.1]non‐7‐endo‐yl benzoate ((−)‐ 43 ) (see Scheme 5). The latter is the precursor of several protected 2,6‐anhydrohepturonic acid derivatives such as the diethyl dithioacetal (−)‐ 57 of methyl 3,5‐di‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐D ‐glycero‐D ‐galacto‐hepturonate (see Schemes 7 and 8). Hydrolysis of (−)‐ 57 provides methyl 3,5‐di‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐D ‐glycero‐D ‐galacto‐hepturonate 48 that undergoes highly diastereoselective Nozaki‐Oshima condensation with the aluminium enolate resulting from the conjugate addition of Me₂AlSPh to (1S,5S,6S,7S)‐7‐endo‐(benzyloxy)‐6‐exo‐{[(tert‐butyl)dimethylsilyl]oxy}‐8‐oxabicyclo[3.2.1]oct‐3‐en‐2‐one ((−)‐ 13 ) derived from (+)‐ 5 (Scheme 12). This generates a β‐C‐mannopyranoside, i.e., methyl (7S)‐3,5‐di‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐7‐C‐[(1R,2S,3R,4S,5R,6S,7R)‐6‐endo‐(benzyloxy)‐7‐exo‐{[(tert‐butyl)dimethylsilyl]oxy}‐4‐endo‐hydroxy‐2‐exo‐(phenylthio)‐8‐oxabicyclo[3.2.1]oct‐3‐endo‐yl]‐L ‐glycero‐D ‐manno‐heptonate ((−)‐ 70 ; see Scheme 12), that is converted into the diethyl dithioacetal (−)‐ 75 of methyl 3‐O‐acetyl‐2,6‐anhydro‐4,5‐dideoxy‐4‐C‐{[methyl (7S)‐3,5,7‐tri‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐L ‐glycero‐D ‐manno‐heptonate]‐7‐C‐yl}‐5‐C‐(phenylsulfonyl)‐L ‐glycero‐D ‐galacto‐hepturonate ( 76 ; see Scheme 13). Repeating the Nozaki‐Oshima condensation to enone (−)‐ 13 and the aldehyde resulting from hydrolysis of (−)‐ 75 , a (1→3)‐C,C‐linked trisaccharide precursor (−)‐ 77 is obtained.     

Structure elucidation of new acacic acid‐type saponins from Albizia coriaria

Three new acacic acid derivatives, named coriariosides C, D, and E ( 1–3 ) were isolated from the roots of Albizia coriaria. Their structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR studies and mass spectrometry as 3‐O‐[β‐D ‐xylopyranosyl‐(1 → 2)‐β‐D ‐fucopyranosyl‐(1 → 6)‐2‐(acetamido)‐2‐deoxy‐β‐D ‐glucopyranosyl]‐21‐O‐{(2E,6S)‐6‐O‐{4‐O‐[(2E,6S)‐2,6‐dimethyl‐ 6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐β‐D ‐quinovopyranosyl}‐2,6‐dimethylocta‐2,7‐dienoyl}acacic acid 28‐O‐β‐D ‐xylopyranosyl‐(1 → 4)‐α‐L ‐rhamnopyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl ester ( 1 ), 3‐O‐{β‐D ‐fucopyranosyl‐(1 → 6)‐[β‐D ‐glucopyranosyl‐(1 → 2)]‐β‐D ‐glucopyranosyl}‐21‐O‐{(2E,6S)‐6‐O‐{4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl]‐β‐D ‐quinovopyranosyl}‐2,6‐dimethylocta‐2,7‐dienoyl}acacic acid 28‐O‐α‐L ‐rhamno pyranosyl‐(1 → 2)‐β‐D ‐glucopyranosyl ester ( 2 ), and 3‐O‐[β‐D ‐fucopyranosyl‐(1 → 6)‐β‐D ‐glucopyranosyl]‐21‐O‐{(2E,6S)‐6‐O‐{4‐O‐[(2E,6S)‐2,6‐dimethyl‐6‐O‐(β‐D ‐quinovopyranosyl)octa‐2,7‐dienoyl)‐β‐D ‐quinovopyranosyl]octa‐2,7‐dienoyl}acacic acid 28‐O‐β‐D ‐glucopyranosyl ester ( 3 ). Copyright © 2010 John Wiley & Sons, Ltd.     

Four Novel Dihydroisocoumarin (=3,4‐Dihydro‐1H‐2‐benzopyran‐1‐one) Glucosides from the Fungus Cephalosporium sp. AL031

Four novel dihydroisocoumarin (=3,4‐dihydro‐1H‐2‐benzopyran‐1‐one) glucosides were isolated from a culture broth of a strain of the fungus Cephalosporium sp. AL031. Their structures were elucidated as (2E,4E)‐5‐[(3S)‐5‐acetyl‐8‐(β‐D ‐glucopyranosyloxy)‐3,4‐dihydro‐6‐hydroxy‐1‐oxo‐1H‐2‐benzopyran‐3‐yl]penta‐2,4‐dienal ( 1 ), (2E,4E)‐5‐[(3S)‐5‐acetyl‐8‐(β‐D ‐glucopyranosyloxy)‐3,4‐dihydro‐6‐methoxy‐1‐oxo‐1H‐2‐benzopyran‐3‐yl]penta‐2,4‐dienal ( 2 ), (3S)‐8‐(β‐D ‐glucopyranosyloxy)‐3‐[(1E,3E,5E)‐hepta‐1,3,5‐trienyl]‐3,4‐dihydro‐6‐hydroxy‐5‐methyl‐1H‐2‐benzopyran‐1‐one ( 3 ), and (3S)‐8‐[(6‐O‐acetyl‐β‐D ‐glucopyranosyl)oxy]‐3‐[(1E,3E,5E)‐hepta‐1,3,5‐trienyl]‐3,4‐dihydro‐6‐methoxy‐5‐methyl‐1H‐2‐benzopyran‐1‐one ( 4 ) by spectroscopic methods, including 2D‐NMR techniques and chemical methods.     

Synthesis and properties of bio‐based polyurethanes bearing hydroxy groups derived from alditols

Four kinds of bio‐based polyurethanes bearing hydroxy groups in the pendants were synthesized by the polyaddition of D ‐mannitol‐ and D,L ‐erythritol‐derived diols (1,2:5,6‐di‐O‐isopropylidene‐D ‐mannitol and 1,2‐O‐isopropylidene‐D,L ‐erythritol) with hexamethylene diisocyanate and methyl (S)‐2,6‐diisocyanatohexanoate and the subsequent deprotection of the isopropylidene groups. They were hydrolyzed much more quickly than the corresponding protected polyurethanes at 50 °C and pH 7.0, although their hydrolytic degradation rate was lower than that of polyurethanes with saccharic and glucuronic lactone groups, which had been reported in our previous articles. The introduction of D ‐mannitol units to the polyether‐polyurethanes containing poly(oxytetramethylene) glycol units also enhanced their hydrolyzibility. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Novel and Stereospecific Synthesis of (2S)‐3‐(2,4,5‐Trifluorophenyl)propane‐1,2‐diol from D‐Mannitol

A stereospecific synthesis of (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol from D ‐mannitol has been developed. The reaction of 2,3‐O‐isopropylidene‐D ‐glyceraldehyde with 2,4,5‐trifluorophenylmagnesium bromide gave [(4R)‐2,2‐dimethyl‐1,3‐dioxolan‐4‐yl](2,4,5‐trifluorophenyl)methanol in 65% yield as a mixture of diastereoisomers (1 : 1). The Ph₃P catalyzed reaction of the latter with C₂Cl₆ followed by reduction with Pd/C‐catalyzed hydrogenation gave (2S)‐3‐(2,4,5‐trifluorophenyl)propane‐1,2‐diol with >99% ee and 65% yield.     

1,3(R):4,6(R)‐Di‐O‐benzyl­idene‐d‐mannitol

The title compound, C₂₀H₂₂O₆, has crystallographic twofold symmetry. The central six‐C‐atom chain has an extended conformation similar to that of d ‐mannitol, with two independent C—C—C—C torsion angles of 165.69 (14) and 177.60 (12)°. The 1,3‐dioxane ring has a chair conformation. All chiral centers have the R configuration.     

Synthetic Study of Carthamin: Biomimetic Synthesis of Carthamin Model via Peroxidase‐Catalyzed Oxidative Decarboxylation of Its Precursor Model

A chiral carthamin model (3S,3′S)‐1‐[5‐acetyl‐2,6‐diketo‐3‐C‐β‐d ‐glucopyranosylcyclohex‐4‐enylidene]‐1′‐[5′‐acetyl‐3′‐C‐β‐d ‐glucopyranosyl‐2′,3′,4′‐trihydroxy‐6′‐oxocyclohexa‐1′,4′‐dienyl]methane, in which two cinnamoyl groups were replaced by an acetyl group, was synthesized by the dimerization of (S)‐2‐acetyl‐4‐C‐(per‐O‐acetyl‐β‐d ‐glucopyranosyl)cyclohexadienone with glyoxylic acid, followed by peroxidase‐catalyzed oxidative decarboxylation and de‐O‐acetylation, or de‐O‐acetylation and peroxidase‐catalyzed oxidative decarboxylation. The corresponding total yields were 12.5% or 17.1% from 3‐C‐(per‐O‐acetyl‐β‐d ‐glucopyranosyl)phloroacetophenone, and the reaction pathway was identical to the biosynthetic pathway.     

Stereoregular poly‐O‐methyl [m,n]‐polyurethanes derived from D‐mannitol

Novel linear carbohydrate‐derived [m,n]‐polyurethanes are successfully prepared using D ‐mannitol as renewable and low cost starting material. The key comonomer, 1,6‐di‐O‐phenylcarbonyl‐2,3,4,5‐tetra‐O‐methyl‐D ‐mannitol is polymerized with a diamine synthesized from D ‐mannitol or with alkylenediamines. These polymerization reactions afford, respectively, a [6,6]‐polyurethane entirely based on a carbohydrate derivative or [m,n]‐polyurethanes constituted by a poly‐O‐methyl substituted unit alternating with a polymethylene chain. All these polymers are stereoregular, as result of the C₂ axis of symmetry of mannitol. The optically active polyurethanes are characterized by standard methods (FTIR, RMN, GPC, TGA, and DSC). Thus, GPC analysis reveals weight‐average molecular weights between 18,000 and 25,000 Da. Thermal studies (DSC) indicate that the polymers obtained are amorphous materials with T_g values dependent on the structure and chain length of the diamine constituent. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Megastigmane Glycosides from Docynia indica and Their Anti‐inflammatory Activities

Using various chromatographic methods, three new megastigmane glycosides, docynicasides A – C ( 1  –  3 ) and ten known, (6S,9R)‐vomifoliol 9‐O‐β‐d ‐xylopyranosyl‐(1′′→6′)‐O‐β‐d ‐glucopyranoside ( 4 ), hyperin ( 5 ), quercitrin ( 6 ), quercetin 3‐α‐l ‐arabinofuranoside ( 7 ), naringenin 7‐O‐β‐d ‐glucopyranoside ( 8 ), phloridzin ( 9 ), phloretin 2′‐O‐β‐d ‐xylopyranosyl‐(1→6)‐β‐d ‐glucopyranoside ( 10 ), pinosylvin 3‐O‐β‐d ‐glucopyranoside ( 11 ), tormentic acid ( 12 ), and chlorogenic acid methyl ester ( 13 ) were isolated from the fruits of Docynia indica. Their chemical structures were elucidated by physical and chemical methods. All the isolated compounds were evaluated for the inhibitory activity on NO production in LPS‐stimulated BV2 cells. As the results, compounds 3  –  5 showed significant inhibitory activity on LPS‐stimulated NO production in BV2 cells with the IC₅₀ values ranging from 21.0 to 29.3 μm .     

Synthesis,Crystal Structures,and Fungicidal Activity of Novel 1,5‐Diaryl‐3‐(glucopyranosyloxy)‐1H‐pyrazoles

Five novel pyrazole‐coupled glucosides, 1,5‐diaryl‐1H‐pyrazol‐3‐yl 2,3,4,6‐tetra‐O‐acetyl‐β‐D ‐glucopyranosides 5a – 5e , were synthesized by the phase‐transfer catalytic reaction of 1,5‐diaryl‐1H‐pyrazol‐3‐ols 4a – 4e with acetobromo‐α‐D ‐glucose in H₂O/CHCl₃ under alkaline conditions, using Bu₄N⁺Br^? as catalyst. Then, glucosides 5a – 5c were deacetylated in a solution of Na₂CO₃/MeOH to yield the 1,5‐diaryl‐3‐(β‐D ‐glucopyranosyloxy)‐1H‐pyrazoles 6a – 6c . Their structures were characterized by ¹H,¹H‐COSY, ¹H‐, ¹³C‐, and ¹⁹F‐NMR spectroscopy, as well as elemental analysis. The structures of 5d and 6c were also determined by single‐crystal X‐ray diffraction analysis. A preliminary in vitro bioassay indicated that compounds 4e and 5d exhibited excellent‐to‐medium fungicidal activity against Sclerotinia sclerotiorum at the dosage of 10 μg/ml.     

Conformational analysis of the disaccharide methyl α‐d‐mannopyranosyl‐(1→3)‐2‐O‐acetyl‐β‐d‐mannopyranoside monohydrate

The crystal structure of methyl α‐d ‐mannopyranosyl‐(1→3)‐2‐O‐acetyl‐β‐d ‐mannopyranoside monohydrate, C₁₅H₂₆O₁₂·H₂O, ( II ), has been determined and the structural parameters for its constituent α‐d ‐mannopyranosyl residue compared with those for methyl α‐d ‐mannopyranoside. Mono‐O‐acetylation appears to promote the crystallization of ( II ), inferred from the difficulty in crystallizing methyl α‐d ‐mannopyranosyl‐(1→3)‐β‐d ‐mannopyranoside despite repeated attempts. The conformational properties of the O‐acetyl side chain in ( II ) are similar to those observed in recent studies of peracetylated mannose‐containing oligosaccharides, having a preferred geometry in which the C2—H2 bond eclipses the C=O bond of the acetyl group. The C2—O2 bond in ( II ) elongates by ～0.02 Å upon O‐acetylation. The phi (?) and psi (ψ) torsion angles that dictate the conformation of the internal O‐glycosidic linkage in ( II ) are similar to those determined recently in aqueous solution by NMR spectroscopy for unacetylated ( II ) using the statistical program MA′AT, with a greater disparity found for ψ (Δ = ～16°) than for ? (Δ = ～6°).