First Enantioselective Synthesis of (2R,3R)-and(2S,3S)-2-(4-hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxan-6-carbaldehyde

Numerous lignans containing 1,4-benzodioxane nucleus represent a class of natural products with cytotoxic and hepatoprotective activities1,2. Recently we have reported the racemic total synthesis of sinaiticin, a flavonolignan of the 1,4-benzodioxane type which was isolated from sinaiticum leaves found in sinai region of Egypt, using 2-(4-hydroxyphenyl)-3-hydroxymethyl-1,4-benzodioxan-6-carbaldehyde as the key interme-diate3,4. This species exhibits significant inhibitory activity against the …     

Synthesis and Crystal Structure of Ethyl 1-（2-bromoethyl）-3-（4-meth-oxyphenyl）-1H-pyrazole-5-carboxylate

The title compound ethyl 1-(2-bromoethyl)-3-(4-methoxyphenyl)-1H-pyrazole-5-carboxylate 1 has been synthesized and structurally characterized by single-crystal X-ray diffraction.The crystal is of monoclinic(C15H17BrN2O3,Mr = 353.22),space group C21 with a = 24.691(7),b = 6.7678(17),c = 17.884(5) ,β = 97.184(5)o,V = 2965.1(13) 3,Z = 8,Dc = 1.583 g.cm-3,F(000) = 1440,μ = 2.784 mm-1,the final R = 0.0260 and wR = 0.0596 for 2684 observed reflections with I > 2σ(I).All the carbon atoms in the molecule are nearly coplanar except C(15),with a large conjugated system among the carbonyl group,pyrazole ring and the benzene ring.Three non-classical intermolecular hydrogen bonds help to stabilize the crystal lattice.The regioselectivity was rationalized based on the coordination of potassium ion with the N-anion and the carbonyl oxygen atom.     

Thermodynamic functions of thermotropic polyethers based on the semiflexible mesogen 1-(4-hydroxyphenyl)-2-(2-methyl-4-hydroxyphenyl)ethane

Heat capacities of a series of thermotropic polyethers consisting of a semiflexible mesogen [1-(4-hydroxyphenyl) - 2 - (2 - methyl - 4 - hydroxyphenyl)ethane], with n methylene flexible spacers (n = 4–12) (MBPE-n) have been measured by DSC and fitted at low temperature to an approximate frequency spectrum, as well as at high temperature to a general equation for the liquid MBPE-n. The latter equation is: C_p = n(17.33 + 0.04551T) + (280.9 + 0.3839T) where n is the number of methylenes in the polyether spacer. The calculated vibration-only heat capacities start to show deviations from the measured heat capacities below the melting temperature, reflecting contributions from conformational disorder and motion in methylene spacers. It is suggested that part of this increase in heat capacity can be looked upon as a glass transition of the partially conformationally disordered crystals. Solid state ¹³C–NMR studies showed similarly that over the range of temperature some of the C? C bonds in the spacer are in a rotational state similar to that in the melt. The equilibrium heats of fusion (ΔH) and the changes of heat capacity (ΔC_p) for the amorphous polymer at the glass transition temperature, T_g, were determined by WAXD and DSC. Based on the discrepancy of ΔC_p it is concluded that these phenylene containing polyethers have a certain amount of rigid amorphous polymer. Thermodynamic functions H, S and G for all of the polyethers have been established.     

Bromo derivatives of 1-(4-hydroxyphenyl)dihydrouracil and 1-(4-hydroxyphenyl)-5- or -6-metehyldihydrouracils

Bromination of 1-(4-hydroxyphenyl)dihydrouracil and its 6-methyl derivative with bromine in refluxing acetic acid gave 1-(3,5-dibromo-4-hydroxyphenyl)-5-bromo-, 1-(3,5-dibromo-4-hydroxyphenyl)-5-bromo-, and 1-(3,5-dibromo-4-hydroxyphenyl)-5-bromo-6-methyldihydrouracils and 1-(3,5-dibromo-4-hydroxyphenyl)-5-methyluracil. 5-Bromo- and 5,5-dibromodihydrouracils were dehydrobrominated, and the same compounds undergo decomposition to 3,5-dibromo-4-hydroxyphenylurea upon alkaline hydrolysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1251–1254, September, 1982.     

Synthesis of some new pyrazolyl-thiazolidinone derivatives starting from 1-(3-chlorophenyl)-3-(4-methoxyphenyl)-1H-pyrazole-4-carboxaldehyde

Russian Journal of General Chemistry - A novel synthetic approach to (E)-1-{[1-(3-chlorophenyl)-3-[(4-methoxyphenyl-1H-pyrazol-4-yl)- methylene]hydrazono}-3-phenylthiazolidin-4-one starting from...     

Synthesis and Crystal Structure of (E)-2-(1-(2-Hydroxy-4-methoxyphenyl)ethylideneamino)-3-(4-hydroxyphenyl)methyl Propionate

(E)-2-(1-(2-Hydroxy-4-methoxyphenyl)ethylideneamino)-3-(4-hydroxyphenyl)methyl propionate (C22H27O6N, Mr = 401.45) has been synthesized by a condensation reaction of paeonol with tyrosin methyl ester hydrochloride, and its structure was determined by IR, NMR, HR MS and X-ray single-crystal diffraction. The crystal belongs to the monoclinic system, space group P21/c, with a = 11.91291(15), b = 9.49947(12), c = 19.8727(3) , β = 106.1104(15)°, V = 2160.60(5)3, Z = 4, Dc = 1.234 g/cm3, μ = 0.739 mm-1, F(000) = 856, R = 0.0466 and wR = 0.1461 for 3859 observed reflections with (Ⅰ> 2σ(Ⅰ)). In the crystal structure, the title compound is constructed by a centrosymmetric dimmer unit composed of a pair of π-π stacking enantiomers, and such units are linked by intermolecular O(5)-H(5)…O(1) and intramolecular N(1)-H(1)…O(1) hydrogen bonds.     

Synthesis of 1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-r-benzimidazoles

Reaction of 2,6-di-tert-butyl-1,4-benzoquinone with o-phenylendiamine gives 2,6-di-tert-butyl-1,4-benzoquinone-4-(N-o-aminophenyl)imine which reacts smoothly with heterocyclic, aromatic and aliphatic aldehydes to form (1-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-substituted benzimidazoles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–485, April, 1990.     

Synthesis of 1-(3',4'-dihydroxyphenyl)-7-(4"-hydroxyphenyl)- 4hepten-3-one

Natural diarylheptanoids have significant bioactivities. Some of them are potent inhibitors against prostaglandin biosynthesizing enzyme (PG synthetase) and 5-lipoxygenase (LT synthetase)1-2. Compound 1 was firstly isolated from Alnus rubra bark3. So far its synthesis has not been reported yet. Herein, we report the synthesis of compound 1. Meantime, compound 24 was also obtianed as an intermediate. Compound 7 and 16 were converted to compound 10 and 18 respectively, because compound 1…     

(S)-2-乙氧基-3-(4-羟基苯基)丙酸乙酯的合成

(S)-2-乙氧基-3-(4-羟基苯基)丙酸乙酯的合成;二乙氧基乙酸乙酯;Horner Wadswordth Emmons反应;催化氢化;化学拆分;（S） 乙氧基（羟基苯基）     

Synthesis of 1-(2-hydroxyphenyl)-2,4-imidazolidinedione derivatives through cyclic transformations of ethyl 2-oxo-3(2H)-benzoxazoleacetate derivatives

A series of ethyl 2-oxo-3(2H)-benzoxazoleacetate derivatives 2 have been synthesized. By reaction with ammonia, primary amines or hydrazine, these compounds 2 were transformed into 1-(2-hydroxyphenyl)-2,4-imidazolidinedione derivatives 4, 5 and 6 , respectively. Some of these new hydantoins 4 , treated with phosphorus oxychloride, gave 3H-2-oxoimidazo[2,1-b]benzoxazole derivatives 9 . Ethyl 2-oxo-3(2H)-benzoxazolepropionate ( 10 ) was prepared by a Michaël reaction of ethyl acrylate with 2-benzoxazolone ( 1a ). With 10 , no cyclic transformation was observed in the presence of ammonia or alkylamine.     

Syntheses of N-(2,4-Dinitrophenyl)nitroazoles

Several N-(2,4-dinitrophenyl)nitroazoles which cannot be obtained by direct nitration of N-phenylazoles have been prepared by condensation of 2,4-dinitrofluorobenzene with the appropriate nitroazoles. The structures of the products are assigned on the basis of their proton magnetic resonance spectra; in all the examples studied, condensations occur at positions remote from the nitro group of the nitroazole.