Phospholes with Reduced Pyramidal Character from Steric Crowding. 2. Photoelectron Spectral Evidence for Some Electron Delocalization in 1-(2,4-Di-tert-butyl-6-methylphenyl)-3-methylphosphole

Photoelectron spectroscopy has been explored as a tool to measure the flattening of the phosphorus pyramid in a phosphole as caused by a large, sterically demanding P-substituent. Earlier PE spectra had shown no difference in ionization energies (IE) for simple phospholes and their tetrahydro derivatives (both around 8.0-8.45 eV). Calculations of the Koopmans IE at the Hartree-Fock 6-31G level for 1-methylphospholane showed that, as is known for nitrogen, planarization at phosphorus markedly reduced the ionization energy value (8.74 to 6.29 eV). A reduction in IE also occurred on planarizing 1-methylphosphole, but to a lesser extent, being offset by increased electron delocalization (8.93 to 7.16 eV). This suggests that experimental comparison of IE for the unsaturated and saturated systems could be used to detect the presence of electron delocalization in the former. The IE experimentally determined for the crowded 1-(2,4-di-tert-butyl-6-methylphenyl)-3-methylphosphole was 7.9 eV, the lowest ever recorded for a phosphole. The corresponding phospholane had IE 7.55 eV. The difference in the values is attributed to electron delocalization in the phosphole. Calculations performed on the related model 1-(2-tert-butyl-4,6-dimethylphenyl)phosphole showed that the P-substituent adopted an angle of 55.7 degrees (DFT/6-31G level; 57.6 degrees at the HF/6-31 level) with respect to the C(2)-P-C(5) plane (for P-phenyl, 67.1 degrees and 68.3 degrees, respectively).     

Platinum Complexes of Phospholes with Reduced Pyramidal Character

Abstract

The synthesis of planarizcd phospholes showing considerable elcctron delocabtion haw been described.^1–3 We now rcport our findings on their complex forming ability with platinum.     

1-(2,4-dihydroxyphenyl)-3-(2,4-dimethoxy-3-methylphenyl)propane, a novel tyrosinase inhibitor with strong depigmenting effects

A series of diarylpropane compounds was isolated by screening a plant extract library for inhibitors of mushroom tyrosinase. The most potent compound, 1-(2,4-dihydroxyphenyl)-3-(2,4-dimethoxy-3-methylphenyl)propane (UP302: CAS# 869743-37-3), was found in the medicinal plant Dianella ensifolia. Synthetic and plant-derived versions of UP302 inhibited mushroom tyrosinase with similar potencies. UP302 inhibited mushroom tyrosinase with K(i)=0.3 microM, in a competitive and reversible fashion. UP302 was 22 times more potent than Kojic acid in inhibiting murine tyrosinase, with IC(50) values of 12 and 273 microM respectively. Experiments on mouse melanoma cells B16-F1 and on human primary melanocytes demonstrated that UP302 inhibits melanin formation with IC(50) values of 15 and 8 microM respectively. Long-term treatment of cultured melanocytes with up to 62 microM of UP302 revealed no detectable cytotoxicity. In a reconstructed skin model (MelanoDerm) topical application of 0.1% UP302 resulted in significant skin lightening and decrease of melanin production without effects on cell viability, melanocyte morphology or overall tissue histology. In conclusion, UP302 is a novel tyrosinase inhibitor that suppresses melanin production in both cultured melanocytes and reconstructed skin with high potency and without adverse side effects.     

Synthesis of 1-(2-ethynyl-6-methylphenyl)- and 1-(2-ethynyl-6-methoxyphenyl)-naphthalene and their cyclization

A Suzuki cross-coupling reaction of hindered 2-bromo-1-trimethylsilylethynylbenzenes with 1-naphthaleneboronic acid yielding (2-ethynylphenyl)naphthalenes has been achieved. Their subsequent cyclization was carried out, giving benzo[c]phenanthrenes, without the use of photochemical procedures.     

3-烷氧基-6-(4-甲苯基)哒嗪的合成及介晶性

哒嗪衍生物是一类重要的芳香杂环化合物,具有某些生理活性。我们发现,含哒嗪环桥连基的化合物具有液晶性。本文采用3,6 二取代哒嗪、对甲苯基硼酸为原料,通过钯催化交叉偶合反应合成了一系列芳基哒嗪类化合物〔3 烷氧基 6 (4 甲苯基)哒嗪〕,并对其介晶性进行了研究。合成路线为:1　实验部分1 1　主要试剂及仪器3,6 二氯哒嗪、对溴甲苯、醇、溶剂等均为国产化学纯。ＶａｒｉａｎＦＴ 80Ａ型核磁共振仪,ＣＤＣｌ3作溶剂,ＴＭＳ内标;Ｐｅｒｋｉｎ Ｅｌｍｅｒ1730型傅立叶变换红外光谱仪,ＫＢｒ压片;显微熔点测定仪,温度计未经校正;Ｃａｒｌ…     

Synthesis of 3-(aminooxoethyl)-6-methyl-1-(thiethan-3-yl)-pyrimidine-2,4-(1H,3H)-diones

A new approach to prepare 2-chloroacetamides has been developed, based on the reaction of chloroacetyl chloride with excess of secondary amines. Alkylation of 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1H,3H)-dione with the synthesized 2-chloroacetamides in the presence of potassium carbonate has afforded N ³-acetamido-substituted 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1H,3H)-diones.     

Synthesis of 5-Methanesulfonamido-6-(2,4-Difluorophenylthio)-1-Indanone

The ethylene ketal of 5-nitro-6-bromo-1-indanone 6 was prepared via oxidation of N-(6-Bromo-5-indanyl)-acetamide 1. A subsequent mild displacement and elaboration to 6-thiosubstituted-5-amino indanone derivative 10 is also described.     

(5S,6R)-2-(4-甲基)苯基-6-[(1R)-叔丁基二甲基硅氧乙基]-青霉烯-3-羧酸乙酯的合成研究

青霉烯[1]类抗生素是近年来发展很快的一种非典型β-内酰胺抗生素.青霉烯类化合物[2]具有广泛的抗菌活性,具有优于碳青霉烯类抗生素的特点,其固体化合物和酯型前药可口服吸收,不易被β-内酰胺酶水解,同时对脱氢肽水解酶-I( DHP-I )较碳青霉烯稳定.     

Molecular structure of 2,4-diacetyl-3-(2-chlorophenyl)-5-hydroxy-5-methyl-N-(4-methylphenyl)-1-cyclohexenylamine

The molecular structure of 2,4-diacetyl-3-(2-chlorophenyl)-5-hydroxy-5-methyl-N-(4-methylphenyl)-1-cyclohexenylamine (Ia) determined by X-ray diffractometry (XRD) is described. Two intramolecular hydrogen bonds: O-H…O=C and N-H…O=C are realized in molecule Ia.     

3-[N-(4-甲基苯基)氨基羰基]-5-[4-(4-甲酸基苯甲氧基)苯亚甲基]-2,4-噻唑烷二酮的合成

以对甲苯胺和对甲基苯甲酸甲酯为起始原料,经NBS溴化、亲核取代、酸水解和Knoevenagel缩合等6步反应合成了抗细菌生物膜化合物—3-[N-(4-甲基苯基)氨基羰基]-5-[4-(4-甲酸基苯甲氧基)苯亚甲基]-2,4-噻唑烷二酮,总收率57.3％,其结构经1H NMR,ESI-MS和元素分析确证.     

(5-甲基-2-烷氧基苯基)-1-烃基胺的合成

以对甲酚(1)为起始原料,经醚化、酰化和还原氨化反应合成了5个(5-甲基-2-乙氧基苯基)-1-烃基胺;1经酯化、Fries重排、醚化和还原氨化反应合成了5个(5-甲基-2-甲氧基苯基)-1-烃基胺.其结构经1H NMR,13C NMR,IR和GC-MS表征.     

Condensation of 5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione with haloacetic acids

Reactions of triazolethiones with haloacetic acids were studied with 5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione as an example. It was proved for the first time by X-ray diffraction that the cyclocondensation of these compounds proceeds regiospecifically to give 2-(4-methylphenyl)[1,3]thiazolo[3,2-b][1,2,4]triazol-6(5H)-one rather than its isomer 3-(4-methylphenyl)[1,3]thiazolo[2,3-c][1,2,4]triazol-5(6H)-one.     

N-[4-氯-2-取代氨基甲酰基-6-甲基苯基]-1-芳基-5-氯-3-三氟甲基-1H-吡唑-4-甲酰胺的合成及生物活性

通过改变传统氯虫酰胺中吡唑环上氨基甲酰基与吡啶环之间的相对位置, 或以其它芳环取代原分子中的吡啶环, 设计合成了24个结构新颖的N-[4-氯-2-取代氨基甲酰基-6-甲基苯基]-1-芳基-5-氯-3-三氟甲基-1H-吡唑-4-甲酰胺类化合物. 所有目标化合物的结构均通过¹H NMR谱、 元素分析或高分辨质谱表征确定. 初步的生物活性测试结果表明, 部分化合物对东方粘虫具有较好的杀虫活性, 其中化合物6m在浓度为50 mg/L时具有80%的杀虫活性. 同时, 在浓度为50 mg/L时目标化合物对5种常见病菌具有明显的抑制作用, 其中化合物6n和6x对苹果轮纹菌的抑菌率达62.1%.     

Electrochemical interconversion of 1-(p-tolyl)-6-methyl-2,4-diphenylpyrimidinium perchlorate and 1-(p-tolyl)-6-methylene-2,4-diphenylpyrimidine

It is shown that reduction of the 6-methyl-1-(p-tolyl)-2,4-diphenylpyrimidinium cation proceeds in two one-electron stages. In the first stage, an unstable radical is formed, and in the second stage, an unstable anion. As a result of dehydrogenation of the radical, the anhydro base 6-methylene-1-p-tolyl-2,4-diphenyl-6H-pyrimidine is formed. Oxidation of this compound in a single one-electron stage forms an unstable cation radical, the hydrogenation of which leads to the original pyrimidinium cation. Data obtained by cyclic voltametry and electrosynthesis with subsequent identification of the products have shown that, the same as in the reaction with the hydroxide anion, the methyl-substituted pyrimidinium cation acts as a CH-acid.Rostov State University, Rostov-on-Don 344101, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 71–75, January, 1999.     

Synthesis,Characterization and X-ray Structure of N-(4-bromobutanoyl-N’-(2-3- and 4-methylphenyl)thiourea

N-4-(bromobutanoyl)-N'-(o-, m- and p-tolyl)thioureas 3a, 3b and 3c respectively, were synthesized by the reaction of 4-bromobutanoylisothiocyanate with p-, m- and o-toludine. The products were characterized by IR, and NMR spectroscopic techniques. The two carbonoylthiourea isomers N-(4-bromobutanoyl)-N'-(3-methylphenyl)thiourea(3b) and N-(4-bromobutanoyl)-N'-(4-methylphenyl)thiourea(3c) were obtained in crystalline form by recrystallization from DMSO. Xray crystallographic studies showed that both compounds 3b and 3c crystallize in triclinic system with space group of P1. The molecules adopt trans-cis configuration with respect to the positions of 4-bromobutanoyl and tolyl groups respectively, against the thiono C=S bond across their C–N bonds. The configuration is attributed by the intrahydrogen bond between the carbonyl oxygen and amide hydrogen atoms. Both crystal structures are stabilized by N–H···S intermolecular hydrogen bonds to form dimers and arranged along the b axis.     

Synthesis of 2,4-(1H,3H)-quinazolinediones

Improved procedures for syntheses of kilogram quantities of quinazolinedione 5 and its intermediates 2,3 and 4 are described. The mechanism of formation of 5 is discussed as well as a side reaction resulting in 7 .