Some transformations of 2-methyl-2-allyl-4-methylol-1,3-dioxolane

Conclusions A study was made of the reaction of 2-methyl-2-allyl-4-methylol-1,3-dioxolane with mercaptans, alcohols, halogens and hydrogen halides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1541–1542, July, 1971.     

固载杂多酸催化合成2,4-二甲基-2-(4-甲基-3-戊烯基)-1,3-二氧五环

环缩酮类香料化合物[1 3]是在催化剂存在下由相应的酮和多元醇经缩合反应而制得。已报道的催化剂有质子酸[1]、固体酸[2,3]和某些金属盐类[4～7]等。本文以大孔阳离子交换树脂固载磷钨酸催化6 甲基 5 庚烯 2 酮与1,2 丙二醇的缩合反应,催化剂活性高,且可重复使用,后处理简便。1　实验1 1　仪器和试剂ＷＹＡ 1Ｓ阿贝折光仪;ＰＥ 2400ＣＨＮ元素分析仪;ＰＥ 783红外光谱仪。6 甲基 5 庚烯 2 酮、1,2 丙二醇、钨酸钠、磷酸氢二钠、盐酸等均为分析纯;大孔阳离子交换树脂(Ｄ001 ＣＣ型)。1 2　制备1 2 1　催化剂　以二水钨酸钠和十二水磷酸氢…     

Aspirin prodrugs: synthesis and hydrolysis of 2-benzyloxy-2-methyl-4H-1,3-benzodioxin-4-ones

Aspirin is widely used for its analgesic, antiinflammatory and antipyretic properties. Among its disadvantages are the relatively narrow therapeutic margin, its irritancy towards the gastric mucosa, and occasionally patient hypersensitivity towards aspirin. As part of our effort to develop prodrugs without these liabilities eleven new title compounds have been isolated and characterized. These 'superaspirin' candidates were subjected to non-enzymatic hydrolysis for a first rapid screening in vitro. Only 2-(2,6-dimethoxybenzyloxy)-2-methyl-4H-1,3-benzodioxin-4-one (4c) was observed to act as an exclusive aspirin prodrug, while 2-(2-methoxybenzyloxy)-2-methyl-4H-1,3-benzodioxin-4-one (4b) and 2-(2-ethoxybenzyloxy)-2-methyl-4H-1,3- benzodioxin-4-one (4d) were shown to release both aspirin 6 and salicylic acid 7. Subsequently, these three candidates were further characterized by investigation of the pH profile of their hydrolysis rates.     

Iodocyclization of N,N-dialkylamino-2-methyl-4-penten-2-ol oxides

It is shown that in the iodination of N,N-dialkylamino-2-methyl-4-penten-2-ol and N,N-diethylamino-3-butene oxides the N-oxide group participates in the intramolecular cyclization of these compounds. N,N-Dialkyl-4-methyl-4-hydroxy-6-iodomethyltetrahydro-1,2-oxazine iodides were obtained by iodination of the former, whereas the latter under similar conditions gives N,N-diethyl-5-iodomethyltetrahydro-1,2-oxazolinium iodide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1340–1343, October, 1976.     

Multicomponent assembling of salicylaldehydes,malononitrile, and 4-hydroxy-6-methyl-2H-pyran-2-one: A fast and efficient approach to medicinally relevant 2-amino-4H-chromene scaffold

A new multicomponent reaction (MCR) was found: a sodium acetate-catalyzed transformation of salicylaldehydes, malononitrile and 4-hydroxy-6-methyl-2H-pyran-2-one in ethanol results in the fast (30 min) and efficient formation of new 4-pyrano-substituted 2-amino-4H-chromenes in 86–96% yields. The same transformation initiated by grinding in mortar in the presence of sodium acetate or potassium fluoride results in a faster (15 min) formation of 4-pyrano-substituted 2-amino-4H-chromenes in 80–90% yields. This novel ‘one-pot’ process opens an effective and convenient way to pyrano-functionalized 2-amino-4H-chromene systems, which are promising compounds for different biomedical applications.     

Enzymatic resolution of 4-methyl-, 4-phenyl- and 6-phenyltetrahydro-2H-pyran-2-one using esterases

Enantioselective hydrolysis of racemic tetrahydro-2H-pyran-2-ones (δ-valerolactones) using esterase resulted in the formation of optically active (R)-4-methyl-, (R)-4-phenyl- or (R)-6-phenyltetrahydro-2H-pyran-2-ones and the corresponding (S)-8-hydroxypentanoic acid derivatives.     

3-甲基-2-戊烯-4-炔醛的合成新方法

化合物3-甲基-2-戊烯-4-炔-1-醛两端均为活性官能团,在分子连接及成环反应中能够起到非常重要的作用,是合成轮烯酮[1-7],脱落酸[8]和二苯基二苯并环辛烯[9]等的重要中间体.     

3-methylthio-1,2-dithiolylium salts : Reaction with 4-hydroxy-6-methyl-2H-pyran-2-one and 4-hydroxycoumarin

The reaction of 4- and 5-aryl-3-methylthio-1,2-dithiolylium iodides with 4-hydroxy-6-methyl-2$\text{H}$-pyran-2-one and 4-hydroxycoumarin has been studied. 4-Substituted salts yielded 3-aryl-7-methyl-2-thioxo-2$\text{H}$,5$\text{H}$-pyrano [3,2-c]pyran-5-ones and 3-aryl-2-thioxo-2H,5H-pyrano[3,2-c]benzo[e]pyran-5-ones, respectively, whereas 5-substituted salts gave rise to 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-6-methyl-2$\text{H}$-pyran-2,4-diones and 3-(5′-aryl-1′,2′-dithiol-3′-ylidene)-2$\text{H}$-benzo [b]-pyran-2,4-diones.     

Products from furans. VI. Synthesis of dihydro-2-disubstituted-2H-pyran-3(4H)-ones,tetrahydro-3-(aminomethyl)-2-(p-methoxyphenyl)-2-methyl-2H-pyran-3-ol derivatives and 6-(p-methoxyphenyl -6-methyl-7-oxa-1,3-diazaspiro[4,5]decane-2,4-dione

Hydrogenolysis of 5,6-dihydro-6-(p-methoxyphenyl)-6-methyl-5-oxo-2H-pyran-2-yl ethyl carbonate yielded dihydro-2-(p-methoxyphenyl)-2-methyl-2H-pyran-3(4H)-one, 3 . Subsequently cyanohydrin 4 , derived from 3 , on reduction afforded 3-(aminomethyl)tetrahydro-2-(p-methoxyphenyl)-2-methyl-2H-pyran-3-ol, 5 . The synthesis of N-dimethyl,N-isopropyl,N-imidazolyl as well as N-oxazolinyl derivatives of 5 is presented. The synthesis of 6-(p-methoxyphenyl)-6-methyl-7-oxa-1,3-diazaspiro[4,5]decane-2,4-dione 10 , a spiro hydantoin prepared from ketone 3 is also reported.     

Synthesis, properties and prodrug potential of 2-methyl-2-oxy- and 2-methyl-2-thio-4H-1,3-benzodioxin-4-ones

The fifty-four known title compounds are fully documented and their chemical and biological properties discussed in detail. Special attention is devoted to their potential as aspirin and salicylic acid prodrugs, respectively.     

Aspirin prodrugs: synthesis of 2-substituted 2-methyl-4H-1,3-benzodioxin-4-ones and their screening for prodrug potential

A series of new 2-substituted 2-methyl-4H-1,3-benzodioxin-4-ones 1 have been synthesized and fully characterized. This study involves fifteen compounds of which fourteen are orthoesters, containing tertiary aliphatic alkoxy groups. One compound contains a tert-butylperoxy group and one a 3 beta-cholesteryloxy group in the 2-position. The hydrolysis of these compounds 1 was followed in enzymatic and non-enzymatic media to clarify whether they are true prodrugs of aspirin. Two compounds 1 were additionally tested in vivo as potential topical keratolytics.     

One-pot synthesis of 1-monosubstituted-1, 2, 3-triazoles from 2-methyl-3-butyn-2-ol

An efficient method for the synthesis of 1-monosubstituted-1, 2, 3-triazoles from 2-methyl-3-butyn-2-ol under copper catalyst conditions has been developed through a one-step one-pot sequence. This method provides a concise and efficient pathway to synthesize 1-monosubstituted-1, 2, 3-triazole derivatives in good to excellent yields.     

Viscosity of aqueous solutions of 2-propyne-1-ol, 2-methyl-3-butyne-2-ol and 3-butene-2-ol

Viscosities of aqueous solutions of 2-propyne-1-ol (propargyl alcohol), 2-methyl-3-butyne-2-ol and 3-butene-2-ol have been measured at temperatures 308.15, 313.15, 318.15, 323.15 and 328.15?K over the entire composition range. Viscosity of the aqueous solutions of 2-methyl-3-butyne-2-ol and 3-butene-2-ol increases up to a maximum value and then starts decreasing almost linearly as the mole fraction of alcohol increases. 2-Methyl-3-butyne-2-ol + water and 3-butene-2-ol + water systems exhibit maxima around 0.5 and 0.2 mole fraction, respectively. Conversely, 2-propyne-1-ol + water system shows a rapid initial increase in viscosity up to 0.3 mole fraction followed by a slow steady increase as the mole fraction of alcohol increases to its pure state. Plots of excess viscosities against mole fraction of organic solutes for all the systems exhibit a sharp increase in η ^E to reach a well defined maxima, after which the curves show a descending trend. The variations of viscosity and excess viscosity with the composition of the mixtures have been interpreted in terms of hydrophobic and hydrophilic interactions between the species forming the mixtures.     

ZnO nanoparticles: a green efficient catalyst for the room temperature synthesis of biologically active 2-aryl-1,3-benzothiazole and 1,3-benzoxazole derivatives

A facile synthetic protocol for the synthesis of 2-aryl-1,3-benzothiazoles and 1,3-benzoxazoles has been demonstrated using ZnO nanoparticles as a mild and efficient heterogeneous catalyst. The reactions using ZnO nanoparticles were very fast (<8 min) and provided excellent yields (>90%) of the products. The catalyst was recycled and reused up to eight times without significant loss of catalytic activity. The potential application of 2-(4-hydroxyphenyl)-1,3-benzothiazole as new acid–base indicator has also been demonstrated in this Letter.     

Vibrational Satellites and Pseudorotation in 2-Methyl-1,3-dioxolane

Vibrational satellites caused by pseudorotation are identified in the microwave spectrum of 2-methyl-1,3-dioxolane. The rotational constants of the satellites are determined up to state v = 6. Splittings between lower pseudorotational energy levels are determined by measuring the relative intensities of rotational transitions. An attempt is made to determine the form of the pseudorotation function of the molecule using the obtained data.     

Polymerization of 1,3-butadiene, 4-methyl-1,3-pentadiene and styrene with catalyst systems based on biscyclopentadienyl derivatives of titanium

1,3-Butadiene, 4-methyl-1,3-pentadiene and styrene were polymerized with dicyclopentadienyltitanium dichloride/methylaluminoxane (Cp₂TiCl₂/MAO) and dicyclopentadienyltitanium chloride/MAO (Cp₂TiCl/MAO). These systems are less active than cyclopentadienyltitanium trichloride/MAO (CpTiCl₃/MAO), but show the same stereospecificity as the latter; they give predominantly cis-1,4-polybutadiene, 1,2-syndiotactic poly(4-methyl-1,3-pentadiene) and syndiotactic polystyrene. Cp₂TiCl/MAO is much more active than Cp₂TiCl₂/MAO; this is probably due to the fact that in the reaction of Cp₂TiCl₂ with MAO, only a small amount of Ti(IV) is reduced to Ti(III), which is the active species in the polymerization of styrene and 1,3-dienes. An interpretation of the structure of the active species in Cp₂TiCl/MAO is reported.     

Convenient synthesis of （4R,5R）-4,5-bis（aminomethyl）-2-isopropyl- 1,3-dioxolane

A convenient approach for the preparation of (4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane is described. The target compound via two steps is synthesized from diethyl-2,3-O-isobutylidene-D-tartrate, through ammonolysis and reduction.