Synthesis and Crystal Structure of 1,4-Bis(2-hydroxymethylphenyl)-1,4-dioxabutane

1 INTRODUCTION Macrocyclic ligands and their metal complexes have received much attention due to their applications in ion transport, ion separation and as models in biomimic researches[1~7]. The synthetic methods of macrocyclic ligands and their metal complexes are mainly divided into three kinds[8]. The first one is synthesizing free ligand, then forming the metal complexes; the second is template synthesis; and the third is synthesizing the end-off or side-off precursor ligand, then c…     

Asymmetric Diels–Alder reactions of 5-substituted and 5,6-disubstituted (S)-2-(p-tolylsulfinyl)-1,4-benzoquinones with cyclopentadiene and trans-piperylene

A systematic study of reactions between 5-substituted and 5,6-disubstituted (S)-2-p-tolylsulfinyl-p-benzoquinones and cyclopentadiene or trans-piperylene is reported. Complete regio and π-facial selectivities are observed. The different behaviours of cyclic and acyclic dienes in the presence of ZnBr₂ (cyclopentadiene showed reversed diastereoselection) and the role of BF₃·OEt₂ are discussed.     

Total Synthesis of (R)-(−)-β-Cuparenone

Abstract

(R)-(?)-β-Cuparenone has been synthesized from (S)-(+)-acid-2 obtained via resolution of the racemic acid. Two of the noteworthy steps are (a) repeated methylation of ester (+)-8 with LDA/MeI to furnish (+)-10 and (b) the reaction of 12, having two neopentyl units with NaCN.     

Synthesis of ( )-5α-Hydroxy-β-selinene and (-)-5β-Hydroxy-β-selinene

Eudesmanederivativeshavebeendrawingconsiderableattentionduetotheirwidespectrumofbiologicalproperties,particularlyantifeedant,cellgroWthinhibitoryandplantgroWthregulatingactivitiesl'2.Recently,twoepimericeudesmanederivatives( )-5a-hydroxy-6-selinene1and(-)-56-hydroxy-6-selinene2wereisolated3fromtheaerialpartsofCSubtraPicaFMell.,andtheirstructuresweredeterminedbyspectroscopicmethods.Herein,wereportafacilesynthesisofbothtwodiastereomers1and2from( )-dihydrocarvone3infivesteps,usingtheregioselect…     

Stereoselective Synthesis of (Z)-β-Aryltellurocinnamic Esters

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Synthesis of 6I-O-(4-Methylbenzenesulfonyl)-β-cyclodextrin

Russian Journal of Organic Chemistry - An improved procedure has been proposed for the synthesis of 6I-O-(4-methylbenzenesulfonyl)-β-cyclodextrin by reaction of β-cyclodextrin with...     

Synthesis and Polymerization of 2-(β-Substituted Acryloyl)-1 -Met hacryloyloxy naphthalenes

Some 2-(β-substituted acryloyl)-l-methacryloyloxy-naphthalenes (II) were synthesized by the reaction of the corresponding 2-(β-substituted acryloyl)-l-naphthols with methacryloyl chloride. These monomers were polymerized with 2, 2′-azoisobutyronitrile. The properties of the resulting oligomers as photosensitive resins are described.     

Synthesis of (S)-(−)-β-cuparenone and (S)-(−)-cuparene

A short and efficient synthesis of the title compounds is described. (S)-(−)-β-Cuparenone was prepared in 31% yield from p-tolualdehyde and mesityl oxide in eight steps. Absolute stereochemistry was established by means of a diastereoselective cyclopropanation using (R,R)-hydrobenzoin as a recoverable auxiliary.     

Synthesis of α-amino-β-keto-esters (β-oxodipeptides)

The synthesis of α-amino-β-keto-esters (β-oxo dipeptides) was studied. Corresponding α-amino-β-ketoesters were prepared from BOC-(L)-Valine and BOC-(L)-isoleucine by coupling with (D,L)-threonine hydrochloride and oxidation with Dess-Martin periodinane (DMP) with a total yield of 48% and 38%, respectively. __________ Translated from Chemistry Online, 2007, 70(10): 793–796 [译自: 化学通报]     

Synthesis of (Methyl-β-cyanoethyl)cyclosiloxanes

Previously unknown (methyl--cyanoethyl)tri-, -tetra-, and -pentacyclosiloxanes were prepared by oxygen-halogen exchange between silicon and tin. The ²⁹Si NMR spectra of the products were measured and interpreted.     

Reaction of (E)-1,1,1-trichloro-3-nitrobut-2-ene with amines: diastereoselective synthesis of N-substituted α-trichloromethyl-β-nitroamines

The addition of primary and secondary amines to (E)-1,1,1-trichloro-3-nitrobut-2-ene proceeded diastereoselectively and led to a number of new N-substituted α-trichloromethyl-β-nitroamines, whose stereochemistry was confirmed by X-ray crystallography and NMR spectroscopy.     

Stereoselective Synthesis of 2-(4-Hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxane-6-aldehyde—The Key Intermediate of Sinaiticin

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Synthesis and Cyclization of N-(4-Phenoxyphenyl)-β-alanines

We have used the reaction of 4-aminodiphenyl ester with acrylic, methacrylic, crotonic, and itaconic acids to synthesize N-substituted -alanines, which undergo ring closure to form derivatives of dihydropyrimidinedione and 4-carboxy-2-pyrrolidinone. We have studied the reactions of acylation and recyclization of the dihydropyrimidinedione ring, and we have synthesized derivatives of 4-carboxy-1-(4-phenoxyphenyl)-2-pyrrolidinone: arylidene hydrazides, 2[(2-oxo-4-pyrrolidinyl-1-(4-phenoxyphenyl)]benzimidazole.     

Synthesis of Guanosine 5′-(β-L-Fucopyranosyl)-Diphosphate Revisited

ABSTRACT

It will be demonstrated that a successful synthesis of β-L-fucopyranose-1-phosphate (2), a key intermediate in the preparation of guanosine 5′-(β-L-fucopyranose)-diphosphate (1), strongly depends on the nature of the acyl protecting groups for the non-anomeric hydroxyl functions. Thus, the perbenzoylated, instead of peracetylated, α-L-fucopyranosyl trichloroacetimidate (11) or the corresponding ethyl β-thiofucopyranoside proved to be a convenient starting compound for the preparation of 2. Further, condensation of N,N′-dicyclohexyl-4-morpholinecarboxamidinium guanosine 5′-morpholidophosphate with excess 2 gave the title compound without concomitant formation of bisguanosine-5′-diphosphate (16).     

Synthesis of (R)- and (S)-β-hydroxyphosphonate acyclonucleosides: structural analogues of Adefovir (PMEA)

A synthetic pathway to new acyclonucleoside phosphonates, as analogues of Adefovir, is described. The reduction of an acyclonucleoside β-ketophosphonate, readily available from the nucleobase and benzylacrylate, afforded a mixture of (R)- and (S)-β-hydroxyphosphonate derivatives which was resolved. The assignment of the absolute configuration was proposed on the basis of NMR studies and was supported by molecular modelling studies.     

Saturation molalities and standard molar enthalpies of solution of α-d-xylose(cr) in H2O(l); standard molar enthalpies of solution of 1,4-β-d-xylobiose(am), and 1,4-β-d-xylotriose(am) in H2O(l)

The saturation molality of α-d-xylose(cr) in water was measured by using HPLC and is m(sat) = (8.43 ± 0.42) mol · kg⁻¹ at T = 298.15 K. It was also established that the anhydrous form of α-d-xylose(cr) is the crystalline form that is in equilibrium with the aqueous solution at T = 298.15 K. Solution calorimetry was used to measure the following standard molar enthalpies of solution at T = 298.15 K: ${\mathrm{\Delta }}_{\text{sol}}{H}_{\text{m}}^{\circ }$ = (12.10 ± 0.12) kJ · mol⁻¹ for α-d-xylose(cr); ${\mathrm{\Delta }}_{\text{sol}}{H}_{\text{m}}^{\circ }$ = −(8.1 ± 2.7) kJ · mol⁻¹ for 1,4-β-d-xylobiose(am); and ${\mathrm{\Delta }}_{\text{sol}}{H}_{\text{m}}^{\circ }$ = −(24.1 ± 6.4) kJ · mol⁻¹ for 1,4-β-d-xylotriose(am). It was observed that both 1,4-β-d-xylobiose(am) and 1,4-β-d-xylotriose(am) were amorphous substances and that they form thick gels in water in which no solid phase is present. Consequently, it is not possible to measure m(sat) for these two substances. All substances were carefully characterized by using both HPLC and Karl Fischer analysis. NMR was used to measure the anomeric purity of the α-d-xylose(cr). Thermodynamic network calculations were used to calculate standard molar formation properties for the aforementioned substances.     

Synthesis and antimicrobial properties of 3-(β-hydroxyethyl)-1,3-oxazolidins

The possibility of synthesis of 3-(β-hydroxyethyl)-1,3-oxazolidin and its substituted derivatives at position 2 by the condensation-heterocyclization of diethanolamine with certain aldehydes and ketones was examined. The structure of the compounds was identifi ed by NMR spectroscopy. We investigated antimicrobial properties of the synthesized compounds against microorganisms that affect the lube oil M-11 and found a dependence of the antimicrobial properties on the nature of the substituent at position 2 of oxazolidin heterocycle.     

Synthesis and structure of N,N′-bis(dihexylphosphorylmethyl)-1,4-diaminobutane

Russian Journal of General Chemistry - N,N′-Bis(dihexylphosphorylmethyl)-1,4-diaminobutane has been obtained via the Kabachnik–Fields reaction. Crystal structure of its salt with nitric...     

Asymmetric Synthesis of Highly Enantiomerically Enriched (S)(-)-β-Bisabolene

(S)-β-Bisabolene, (S)-1, was synthetized by a synthetic route in which (S)-4-methyl-3-cyclohexene carboxylic acid, (S)-10, which was the key intermediate, was prepared via a highly diastereoselective TiCl₄-catalyzed Diels-Alder reaction between isoprene and the acrylate of commercial (R)-pantolactone, followed by hydrolysis. Compound (S)-10 was then converted into ketone (S)-13 using two different procedures. The best one of these, as regards the degree of stereospecificity, involved the reaction of (S)-10 with 2 equiv of 4-methyl-3-penten-1-yllithium, 14, in the presence of CeCl₃, and gave (S)-13 having ca. 84% ee. The Zr-promoted methylenation of this ketone afforded highly enantiomerically enriched (S)-1.