Synthesis of New Dioxacyclophanes Derived from 1,1′-Binaphthyl-2, 2′-diol

Abstract

The Williamson reaction between (R,S)-[1,1′-binaphthyl]-2, 2′-diol 1 and (R,S)-2,2′-bis (bromomethyl)-1,1′ binaphthyl 2 in acetone, gave the diastereoisomeric dioxacyclophanes (R?, S?)-3a and (R?, R?)-3b in high yield.     

1,1′-Spirobiindane-7,7′-diol: a novel,C2-symmetric chiral ligand

A novel, C₂-symmetric chiral diol (16) was prepared in six steps from m-anisaldehyde and resolved via its bis-l-menthoxycarboxylate.     

Total synthesis of lycopene-5,6-diol and γ-carotene-5′,6′-diol stereoisomers and their HPLC separation

Lycopene-5,6-diol stereoisomers (1a,b) and (2a,b) and γ-carotene-5′,6′-diol stereoisomers (3a,b) and (4a,b) were synthesized by a stepwise C₁₅ + C₁₀ + C₁₅ double Wittig reaction strategy. The key compounds erythro(anti)-C₁₅-dihydroxy aldehydes 17a,b and their threo(syn)-stereoisomers 23a,b were prepared via Sharpless asymmetric epoxidation of geraniol and nerol followed by acidic hydrolysis of the epoxides in a stereospecific manner. The enantiomerically enriched anti-isomers were obtained by way of recrystallization of 2,3-epoxygeranyl 3,5-dinitrobenzoates 9a,b, whereas syn-isomers were obtained as enantiomerically pure forms via recrystallization of dihydroxyneryl 3,5-dinitrobenzoates 21a,b. In order to determine the absolute stereochemistry of natural products, HPLC separation methods for each enantiomers 1a,b–4a,b were established by using a column carrying a chiral stationary phase.     

Synthesis of 1′-substituted 4′,4′-dimethyl-6′-methoxy-4′H-spiro[cyclohexane-1,3′-isoquinolines]

The reaction of 1-(4-methoxyphenyl)-1-(1-methylcyclohexyl)ethanol with nitriles in concentrated sulfuric acid afforded 1′-substituted 6′-methoxy-4′,4′-dimethyl-4′H-spiro[cyclohexane-1,3′-isoquinolines] as a result of consecutive Wagner-Meerwein rearrangement and Ritter reaction.     

Isolation and Crystal Structure of Stigmast-4-ene-3,6-diol

1 INTRODUCTION Stigmast-4-ene-3,6-diol was first isolated from the marine natural products, and its crystal structure has not yet been reported. In the course of our systematic search for bioactive substances from marine organisms, we have obtained t…     

First Total Syntheses of 4′-0-Geranylisoliquiritigenin And 4′-O-Geranylnarigenin

The title compounds, 4'-0-geranylisoliquiritigenin and 4'-0-geranylnaringenin isolated from Millettia ferruginea and Borania coerulescens respectively, were first synthesized starting from geranyl bromide, 4-hydroxybenzaldehyde and O-hydroxy acetophenones by the condensation reaction and demethoxymethylation as key steps.     

Optical Rotatory Feature of (R or S)-1,1′-Binaphthalene-2,2′-diol (BINOL) in Various Solvents

IntroductionElieletal.1,2 haveeverreportedthatsolventtypeandconcentrationwouldaffecttheequilibriumofcis 3 hydrox ythiane S oxideconformationwhichwascausedbyintermolec ularandintramolecularhydrogenbondformedwiththeinter actionbetweenthesolute solventandthesolute soluteinthesolutionandhaveimportantinfluenceonitsspecificrotation .Uptonowitisnotveryclear,however,whetherhydrogenbondingaffectsspecificrotation (inmagnitudeandoccasion allyinsign)directlyorwhetheritdoessoindirectly (byaf fectingconform…     

Investigations of 2,3′-biquinolines 23. Synthesis of 1′-R-1′,4′-dihydro-2,3′-biquinolin-4′-ones by Claisen condensation

A method has been developed for the synthesis of 1′-R-1′,4′-dihydro-2,3′-biquinolin-4′-ones based on the interaction of quinaldine with N-alkyl-N-formylanthranilic acid methyl esters under the conditions of the Claisen condensation. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 409–410, March 2008.     

4 氨基4′ 氰基联苯的合成

４氨基４′氰基联苯,不仅是制备烷氧基联苯的原料,而且可以制备高正介电各向异性液晶及系列酯类液晶材料．但通常要经过酰化、氧化、酰氯化、氨解、脱水、硝化和还原［１］等多步反应,步骤长、收率低,本文用联苯为原料,经过硝化、碘代、氰代和还原反应合成４氨基４′氰基联苯．反应步骤及时间比原路线减少近一半,而且反应条件温和,收率高．联苯（ＣＰ,上海化学试剂一厂）;Ｎ,Ｎ二甲基甲酰胺（ＡＲ,临平化工试剂厂）;氯仿（ＡＲ,沈阳试剂一厂）;亚硫酸氢钠（ＡＲ,大连辽南化学品厂）;碘酸（ＡＲ,北京化工厂）…     

An Efficient Preparation of 4, 4′-Dicarboxy-2, 2′-Bipyridine

A convenient and high yield preparation of 4, 4′-dicarboxy-2, 2′-bipyridine from the oxidation 4, 4′-dimethyl-2, 2′-bipyridine with potassium dichromate in sulfuric acid is reported.     

Calorimetric study of 2′-methylacetophenone and 4′-methylacetophenone

Values of the condensed phase standard (p = 0.1 MPa) molar enthalpy of formation for 2′- and 4′-methylacetophenones were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The values of the standard molar enthalpy of vaporization, at T = 298.15 K, were measured by Calvet microcalorimetry. Combining these two values, the following enthalpies of formation in the gas phase, at T = 298.15 K, were then derived: 2′-methylacetophenone, –(115.7 ± 2.4) kJ · mol⁻¹, and 4′-methylacetophenone, –(122.6 ± 2.4) kJ · mol⁻¹. Substituent effects are discussed in terms of stability and compared with other similar compounds. The value of the standard molar enthalpy of formation for 3′-methylacetophenone was estimated from isomerization schemes.     

Synthesis of helical shaped 1,1′-bibenzo[c]phenanthrene-2,2′-diol (HEBPOL) derivatives by reduction of helical quinones

A new class of helical shaped bi-phenol (1,1′-bibenzo[c]phenanthrene-2,2′-diol; HEBPOL) type derivatives 2a–g were synthesized from quinone derivatives using the conventional 5% Pd-C catalytic reduction process. We obtained excellent yields for all of the 2a–g derivatives. The HEBPOLs were characterized by different analytical techniques including FTIR, ¹H NMR, ¹³C NMR, MS and X-ray crystallography.     

Some 2′-Modified 4′-Thionucleosides via Sulfur Participation and Synthesis of Thio-Azt from 4′-Thiofuranoid 1,2-Glycal

ThioAZT 14 was synthesized in eight steps from D-arabinose derivative 4 via the new thiofuranoid 1,2-glycal, 5-O-Acetyl-1,2,4-trideoxy-1,4-epithio-3-O-p-toluenesulfonyl-D- threo -pent-1-enitol ( 8 ). Ribosylation of the thiosugar 6 with thymine afforded regioselectively the nucleoside 16 . Treatment of 16 with sodium azide in hot DMF gave, after spontaneous intramolecular displacment, the 2'-azido-xylo derivative 18 , which furnished the free nucleoside 19 on treatment with methanolic ammonia. Similarly, treatment of 16 with sodium ethylthiolate in boiling methanol led to inversion in configuration and gave, after several intramolecular displacments, via the sulfur participation, the 2',3'-diethylthiolate-ribo derivative 23 . Deblocking of 23 with methanolic ammonia afforded the free nuclaoside 24 .     

X-ray diffraction study of 1,5-bis-(4′,4′,4′-trifluoro-1′-methyl-3′-oxo-but-1′-enylamino)-3-oxapentane

Specific features of the molecular and crystal structures of 1,5-bis-(4′,4′,4′-trifluoro-1′-methyl-3′-oxo-but-1′-enylamino)-3-oxapentane are determined by single crystal XRD.     

1′-Azido- and 1′-amino-1,3-dioxolan-4-ones

1,3-Dioxolanone alcohols, prepared via the addition of chiral lithium enolates of 1,3-dioxolan-4-ones to aldehydes, are suitable intermediates for the synthesis of chiral trisubstituted isoserines or trisubstituted 3-hydroxy-β-lactams. In particular, the methyl ester of 2-methyl-3-(2-furyl)isoserinic acid and two 3-methyl-3-hydroxy-β-lactams bearing either a 2-furyl or a phenyl substituent at C-(4) have been prepared. The (2R,3S) stereochemistry of the isoserine, and the (3R,4S) stereochemistry of the two β-lactams is that required for the synthesis of taxoid analogues having the side-chain with the proper (2′R,3′S) configuration.     

Isolation and Crystal Structure of Stigmast-4-ene-3β,6β-diol

The title compound (C29H50O2, Mr = 430.69) was isolated from the algae Halimeda xishaensis collected from the South China Sea. Its crystal structure was determined by single-crystal X-ray diffraction for the first time. The crystal belongs to orthorhombic, space group P212121 with a = 8.1560(13), b = 10.7861 (18), c = 29.973(5) A, V = 2636.8(8)A3, Z = 4, Dc = 1.085 g/cm3, F(000)= 960, μ(Mo-Ka) = 4.533 mm-1, λ = 0.71073 A, S = 1.061, (△ρ)max= 0.382 and (△ρ)min= -0.244e/A3. The structure was refined to R = 0.0561 and wR = O. 1553 for 2711 observed reflections with I ＞ 2σ(I). X-ray diffraction analysis reveals that the title compound has two β-OH groups, and the side chain is saturated. There exist two intermolecular hydrogen bonds between three molecules.     

Preparation of (4′S) and (4′R)-Spiro(oxirane-2-4′-5α-cholestan-3′β-ol), Potent Inhibitors of 4-Methyl Sterol Oxidase

(4′R)- and (4′S)-Spiro(oxirane-2,4′-5α-cholestan-3′β-ol) (1) and (2) were made from (4′R)- and (4′S)-spiro(oxirane-2,4′-5α-cholestan-3-one) (8) and (9). Alkaline hydrogen peroxide oxidation of 4-methylene-5α-cholestan-3-one (7) gave compounds (8) and (9) as a readily separable (1:1) mixture. Reduction of (9) to (2) provided access to a compound which could not be made by other methods.