2′-O-乙酰基-3-酮基-10,11-脱水-12-O-咪唑酰基-6-O-甲基红霉素的合成

以2′-O-乙酰基-3-羟基-11,12-环碳酸酯-6-O-甲基红霉素为原料,通过DMSO/P2O5氧化其3-羟基;再以六甲基二硅胺基钠为碱,经消除、咪唑酰基化"一锅煮"方法合成了抗生素泰利霉素的关键中间体--2′-O-乙酰基-3-酮基-10,11-脱水-12-O-咪唑酰基-6-O-甲基红霉素,总收率68.3%.     

3-羟基-6-O-甲基红霉素的氧化

3-酮基-红霉素化合物是合成酮内酯化合物的关键中间体,由相应的3-羟基红霉素化合物氧化得到.本文对3-羟基-6-O-甲基红霉素(Ⅱ)生成3-酮基化合物(Ⅴ)的氧化反应进行了研究.Ⅱ经乙酰化、碳酸酯化保护后,采用五氧化二磷(P2O5)和乙酸酐(Ac2O)作为活化剂的二甲基亚砜法对其氧化.结果表明,两者在室温下,即能将保护后的Ⅱ转化为目标化合物Ⅴ.Ⅴ的得率分别为85.8%和78.3%.这两种氧化方法成本低、安全性好、环境友好并容易操作,具有规模化生产的前景.     

克拉霉素的合成新方法

以醚化剂1-乙氧基环己烯和硅烷化试剂1,1,1,3,3,3-六甲基二硅氨烷为保护试剂, 采用醚化-硅烷化保护法制备了克拉霉素. 以红霉素A肟为原料计算, 经肟羟基醚化、2',4"-OH硅烷化、6-OH选择性甲基化、脱保护至克拉霉素, 四步反应总收率为49.5%.     

3-羟基克拉霉素和2''-乙酰基-3-氧代克拉霉素的合成与晶体结构

克拉霉素在不同条件下水解,分别生成3-羟基克拉霉素(2)和3-羟基-8,9,10,11-二脱水-9,12-半缩酮克拉霉素(3),用乙酸酐保护2的C(2')-OH得到2'-乙酰基-3-羟基克拉霉素(4),用Ⅳ-氯代琥珀酰亚胺(NCS)氧化4的C(3)-OH合成了2'-乙酰基-3-氧代克拉霉素(5),采用MS,IR,1H NMR,13C NMR等对这些化合物进行了表征.用X射线单晶衍射法测定了化合物2和5的晶体结构,其均属于正交晶系,P212121空间群.化合物2的晶胞参数a=1.3657(3)nm,6=1.4783(3)nm,c=1.6510(3)nm,Z=4,V=3.3332(12)am3,Dc=1.175 g/cm3,F(000)=1288,μ=0.087mm-1;化合物5的晶胞参数a=1.5124(3)nm,b=1.5247(3)nm,c=1.5288(3)nm,Z=4,V=3.5254(12)nm3,Dc=1.187g/cm3,F(000)=1368.0,μ=0.088 mm-1.     

3-羟基-1-金刚烷甲基乙烯基醚的合成

以3-羟基-1-金刚烷甲醇和乙炔为原料,庚烷为溶剂,叔丁醇钾为催化剂,氧化锌为助催化剂,于140℃/1.0 MPa反应3.0 h合成了3-羟基-1-金刚烷甲基乙烯基醚,收率85%,纯度≥99.5%,其结构经IR确证。     

2-甲基-4-羟基-6-苯基嘧啶和2-甲基-4-羟基-5-溴-6-苯基嘧啶的高效液相色谱法分离测定

采用ODS-C18色谱柱和紫外检测器,对2-甲基-4-羟基-6-苯基嘧啶和2-甲基-4-羟基-5-溴-6-苯基嘧啶的含量进行HPLC分离测定.以甲醇水=4555为流动相,紫外检测波长为237 nm,样品线性范围为0.001～0.1 mg/mL.2-甲基-4-羟基-6-苯基嘧啶的RSD为0.5%;2-甲基-4-羟基-5-溴-6-苯基嘧啶的RSD为1.0%.     

2'''',4″-O-双(三甲基硅)-6-O-甲基红霉素A9-O-(1-甲氧基环己基)肟的区域选择性合成机理及其晶体结构

克拉霉素(Clarithromycin)是第二代十四元大环内酯抗生素, 其合成是保护技术应用和区域选择性研究的一次集中体现[1,2].目前, 美国雅培实验室和日本大正公司是以2′,4″-O-双(三甲基硅)红霉素A 9-O-(1-异丙氧环己基)肟(1)作为区域选择性前体制备的[1,3]; 而中国和印度制药企业多采用2′,4″-O-双(三甲基硅)红霉素A 9-O-(1-甲氧基-1-甲基乙基)肟(2)作为关键中间体[4,5].后者的主要杂质为6,11-O-双甲基红霉素A[6].对大环内酯的区域选择性进行了大量的研究后, 发现2′,4″-O-双(三甲基硅)红霉素A 9-O-(1-甲氧基环己基)肟(3)的区域选择性远低于空间结构差异不大的化合物1[7], 却与空间结构差异较大的化合物2一样, 易生成大量的6,11-O-双甲基化产物.     

3-羟基克拉霉素和2′-乙酰基-3-氧代克拉霉素的合成与晶体结构

克拉霉素在不同条件下水解, 分别生成3-羟基克拉霉素(2)和3-羟基-8,9,10,11-二脱水-9,12-半缩酮克拉霉素(3), 用乙酸酐保护2的C(2’)-OH得到2′-乙酰基-3-羟基克拉霉素(4), 用N-氯代琥珀酰亚胺(NCS)氧化4的C(3)—OH合成了2’-乙酰基-3-氧代克拉霉素(5), 采用MS, IR, 1H NMR, 13C NMR等对这些化合物进行了表征. 用X射线单晶衍射法测定了化合物2和5的晶体结构, 其均属于正交晶系, P212121 空间群. 化合物2的晶胞参数a＝1.3657(3) nm, b＝1.4783(3) nm, c＝1.6510(3) nm, Z＝4, V＝3.3332(12) nm3, Dc＝1.175 g/cm3, F(000)＝1288, μ＝0.087 mm－1; 化合物5的晶胞参数 a＝1.5124(3) nm, b＝1.5247(3) nm, c＝1.5288(3) nm, Z＝4, V＝3.5254(12) nm3, Dc＝1.187 g/cm3, F(000)＝1368.0, μ＝0.088 mm－1.     

一步法合成9-去氧-8a-氮杂-8a-同型红霉素A

以(9Z)-9-去氧-9-羟基亚胺基红霉素A为原料,甲醇/水为反应体系,对甲苯磺酰氯为催化剂,硼氢化钠为还原剂,首次用一步法合成了9-去氧-8a-氮杂-8a-同型红霉素A,其结构经1H NMR和FAB-MS表征。在pH8~9,于-3℃反应9 h的较佳反应条件下,收率94.1%,纯度93.0%。     

水相中“一锅法”合成1-[(5-甲基异噁唑-3-氨基)-(苯基)]甲基-2-萘酚

在硫酸钠的存在下,以环境友好的水为溶剂,将苯甲醛、2-萘酚和5-甲基-3-氨基异噁唑通过"一锅法"制备得到了收率为92%的1-[(5-甲基异噁唑-3-氨基)-(苯基)]甲基-2-萘酚,并经过~1H NMR、~(13)C NMR和元素分析进行了表征.同时,对目标产物产率的影响因素进行了考察,得到了优化的合成条件.     

选择性合成手性八氢NOBIN和四氢NOBIN

通过部分氢化手性的(S)-NOBIN [(S)-2-氨基-2’-羟基-1,1’-联萘]选择性地合成了(S)-H8-NOBIN和(S)- -NOBIN. 弱极性溶剂(环己烷)和强极性溶剂(2,2,2-三氟乙醇和含乙酸的乙醇)几乎专一地得到(S)-H8-NOBIN (92%). 而中等极性溶剂(甲醇, 乙醇和异丙醇)以中等产率得到(S)- -NOBIN (66%).     

用气相色谱法研究乙酸乙烯酯不对称氢甲酰化反应中溶剂的影响

用毛细管气相色谱、色－质谱和旋光色散及圆二色性谱仪等方法对乙酸乙烯酯在非极性和极性溶剂中的不对称氢甲酰化反应产物进行分离和鉴定。实验结果表明,在非极性溶剂中反应的收率、选择性、光学收率ｅ．ｅ．值（ｅｎａｎｔｉｏｍｅｒｉｃｅｘｃｅｓｓ）均比极性溶剂中的结果为好。由此探讨了不对称氢甲酰化反应中溶剂的影响。     

Mechanisms of solvolyses of acid chlorides and chloroformates. Chloroacetyl and phenylacetyl chloride as similarity models

[reaction: see text] Rate constants and product selectivities (S = ([ester product]/[acid product]) x ([water]/[alcohol solvent]) are reported for solvolyses of chloroacetyl chloride (3) at -10 degrees C and phenylacetyl chloride (4) at 0 degrees C in ethanol/ and methanol/water mixtures. Additional kinetic data are reported for solvolyses in acetone/water, 2,2,2-trifluoroethanol(TFE)/water, and TFE/ethanol mixtures. Selectivities and solvent effects for 3, including the kinetic solvent isotope effect (KSIE) of 2.18 for methanol, are similar to those for solvolyses of p-nitrobenzoyl chloride (1, Z = NO(2)); rate constants in acetone/water are consistent with a third-order mechanism, and rates and products in ethanol/ and methanol/water mixtures can be explained quantitatively by competing third-order mechanisms in which one molecule of solvent (alcohol or water) acts as a nucleophile and another acts as a general base (an addition/elimination reaction channel). Selectivities increase for 3 as water is added to alcohol. Solvent effects on rate constants for solvolyses of 3 are very similar to those of methyl chloroformate, but acetyl chloride shows a lower KSIE, and a higher sensitivity to solvent-ionizing power, explained by a change to an S(N)2/S(N)1 (ionization) reaction channel. Solvolyses of 4 undergo a change from the addition/elimination channel in ethanol to the ionization channel in aqueous ethanol (<80% v/v alcohol). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions, calculated using Gaussian 03 (HF/6-31G(d), B3LYP/6-31G(d), and B3LYP/6-311G(d,p) MO theory).     

Photoaddition of water and methanol to 2,2,4,6-tetramethyl-1,2-dihydroquinoline

Products of the steady-state photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline (1) in water, methanol, and water—ethanol were isolated for the first time and identified by¹H and¹³C NMR spectroscopy, IR spectroscopy, and mass spectrometry. As a result of the photolysis, the molecule of the solvent is added to the double bond of the heterocycle with formation of 4-hydroxy- (2) or 4-methoxy-2,2,4,6-tetramethyl-1,2,3,4-tetrahydroquinoline (3) in water and methanol, respectively. Compounds2 and3 are converted gradually into1 in the dark. The rate of the back reaction depends on the solvent and the concentration of the product. Comparison of the products of the photolysis in methanol and hexane at 45 °C and of the azoisobutyronitrile-initiated oxidation of1 at the same temperature has shown that unlike the photolysis in hexane, aminyl radicals are not precursors of the product of the photolysis in methanol. The reaction proceedsvia an excited singlet state. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2072–2077, November, 1999.     

Molecular dynamics study of the methanol effect on the membrane morphology of perfluorosulfonic ionomers

The membranes of a perfluorosulfonic acid polymer swollen in 10-80 wt % methanol solution were investigated to elucidate the methanol effect on their morphologies, such as size of the solvent cluster, solvent location, and polymer structure, by using isothermal-isobaric molecular dynamics simulations. In higher methanol concentrations, we found less-spherical solvent aggregation and a more spread polymer structure because of the ampholytic nature of methanol. The partial radial distribution functions between solvent oxygen and fluorocarbons, which are composed of the main chain, clearly show that methanol is located closer to the polymer matrix than water. On the other hand, water is preferentially located in the vicinity of an acidic headgroup, SO(3)(-), compared with methanol, although both have similar attractive interaction energies to the acidic group. Furthermore, we discussed solvent dynamics and hydrogen bonding between sulfonic oxygen and solvent O-H groups.     

顺, 顺-1,5-环辛二烯的单重态氧反应及其产物的重排

本文报道用竹红菌甲素作光敏剂匹配高压钠灯光源, 对1,5-环辛二烯(1)进行单重态氧氧化反应, 高产率和立体选择性地得到顺-5,8-二(氢过氧基)-1,3-环辛二烯(7). 证明了7还原产物顺-5,8-二烃基-1,3-环辛二烯(8)热重排的产物是6-羟基-4-环辛烯酮(3). 而不是6-羟基-3-环辛烯酮(6). 并讨论了热重排过程的机理.     

有机相中利用脂肪酶催化的醇解反应拆分炔丙醇酮乙酸酯

 研究了有机相中脂肪酶催化的炔丙醇酮乙酸酯的立体选择性醇解反应, 考察了碱的种类、酰基受体和溶剂等对反应的影响. 结果表明, 以四氢呋喃为溶剂, CH3OH 为酰基受体, Lipase PLG 脂肪酶为催化剂, Na2CO3 为碱性添加剂, 高底物浓度下 40 oC 反应 96 h 后, 底物转化率和产物 ee 值分别达到 49.5% 和 99.5%. 碱的添加极大地提高了反应速度.     

2-(Perfluoroalkyl)ethanols by Thermal Alkylation of Ambidentate Lactams with 2-(Perfluoroalkyl)-1-iodoalkanes, in the Presence of Added Water. A Change in Mechanism and Stoichiometry of the Reaction. Isolation of a Water Adduct of the Lactim Ether Intermediate

Thermal alkylation of amides by an alkyl halide gives alcohols and esters, and the intriguing behavior of ambidentate lactams in this reaction with 2-(perfluoroalkyl)-1-iodoethanes and lactam 2 is summarized in Scheme 1. 2-(Perfluoroalkyl)ethanols (3) are the principal alkylation product, and there is obtained a range of coproducts in varying amounts. A lactim ether salt (6.HI) is the first reaction intermediate in a sequence of reactions. For delta-valerolactam (8) or epsilon-caprolactam (11), conversion to 3 falls precipitously and R(F)CH=CH(2) (4) becomes a major product. However, when water is introduced, alkylation rate of 2 by iodoalkane 1 increases, the conversion to 3 and 4 decreases, and a new lactim ether salt, 7.HI (the water adduct of 6.HI), is formed. Conversion to 3 is suppressed because coproduct 2 is weakly basic and the equilibrium lies on the side of the basic amine salt (7.HI). The mass spectrum of 2-hydroxy-2-[[(2-(perfluorohexyl)ethyl]oxy]pyrrolidine (7) includes the parent ion and a fragment (m/z = 131) of the intact pyrrolidine ring with an attached hydroxy group. Basic hydrolysis of product mixtures containing 7.HI in a protic solvent gives a high yield of 3 and 2. The higher lactams, 8 or 11, with 1 and water give the lactam salts efficiently; yield of 4 is low and yield of 3, by subsequent reaction with base, is high. With water present, the reaction rates of 8 and 1 are greater than for 2 and 1; water increases both the alkylation step and the water displacement step. Improved homogeneity of reaction mixtures and a specific solvent effect in which water stabilizes the bipolar transition state may be responsible for improved rates and yields.     

Crystal structure of three solvated Alpinumisoflavones

Single crystals of alpinumisoflavone, C₂₀H₁₆O₅, {systematic name: 5-hydroxy-7-(4 hydroxyphenyl)-2, 2-dimethyl-2H, 6H-benzo [1, 2-b: 5, 4-b′]-dipyran-6-one}, solvated with water, methanol, and ethanol, have been obtained. The incorporation of the solvent molecules into the crystal structure creates a new short inter-molecular O–H···O and C–H···O contacts between the alpinumisoflavone moiety and its solvate molecule. The temperatures at which the solvated molecules lose their solvent molecules are 53, 54, and 65 °C for water, methanol, and ethanol, respectively. The observed temperatures at which the solvates efflorescence are reflective of the progressive increase in mass of the solvates from water to ethanol in the series. The benzopyrone moiety shows the usual planar conformation with the pyran ring deformed into a half-chair conformer as seen previously in the other analogous compounds with puckering parameters [Å], 0.2656(8), 0.3703(8), and 0.3957(9), respectively, for the water, ethanol, and methanol solvates. These are higher than the non-solvated alpinumisoflavone compound previously studied. The size of a substituent group proximal to the keto group has a more pronounced effect on the degree of puckering than substitution on the terminal phenyl ring. The attached phenyl ring shows consistent out-of-plane twist from the mean plane of the benzopyrone system as observed previously for this class of compounds. The observed dihedral angles are 30.26(3), 37.75(3), and 34.00(3)°, respectively, for the water, methanol, and ethanol solvates.