DFT study and Monte Carlo simulation on proton transfers of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water

Density functional theory (DFT) and Monte Carlo (MC) simulation with free energy perturbation (FEP) techniques have been used to study the tautomeric proton transfer reaction of 2-amino-2-oxazoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline in the gas phase and in water. Two reaction pathways were considered: the direct and water-assisted transfers. The optimized structures and thermodynamic properties of stationary points for the title reaction system in the gas phase were calculated at the B3LYP/6-311+G(d, p) level of theory. The potential energy profiles along the minimum energy path in the gas phase and in water were obtained. The study of the solvent effect of water on the proton transfer of 2-amino-2-oxozoline, 2-amino-2-thiazoline, and 2-amino-2-imidazoline indicates that water as a solvent is favorable for the water-assisted process and slows down the rate of the direct transfer pathway.     

Ruthenium(II) complexes derived from 2‐phenylthiazoline‐4‐carboxylic acid: structure and catalytic activity for transfer hydrogenation reaction

Piano‐stool ([(p‐cymene)Ru(thz)Cl], 2 ) and six‐coordinated ([Ru(thz)₂(PPh₃)₂], 3 ) ruthenium complexes derived from 2‐phenylthiazoline‐4‐carboxylic acid (Hthz, 1 ) were synthesized for the first time, and fully characterized using conventional methods. Also, the molecular structure of complex 3 was determined using X‐ray analysis. These complexes were evaluated as catalysts for transfer hydrogenation of carbonyl compounds in the presence of isopropyl alcohol and KO^tBu. Complex 2 was found to be more active than 3 in transfer hydrogenation. Copyright © 2016 John Wiley & Sons, Ltd.     

Ring-contraction from benzo[b][1,4]thiazines to benzo[d]thiazolines induced by oxygen

An unexpected ring-contraction from benzo[b]pyrazino[1,2-d][1,4]thiazine-1,4-diones (6) to benzo[4,5]thiazolo[3,2-a]pyrazine-1,4-diones (7) has been developed. The preliminary mechanistic studies showed the transformation contained two independent steps: the first step is the formation of a Michael adduct upon the addition of the protic solvent, in the presence of base, to the C-2-C-3 double bond of compound 6, and the second step is a ring-contraction induced by oxygen via the migration of sulfur atom from C-2 to C-3 position. And its scope is also studied.     

Novel chiral thiazoline‐containing N―O ligands in the asymmetric addition of diethylzinc to aldehydes: substituent effect on the enantioselectivity

Several novel chiral thiazoline primary and tertiary alcohols were easily synthesized from commercially available l ‐cysteine in three steps and with high yield. These ligands were subsequently applied to the asymmetric addition of diethylzinc (Et₂Zn) to various aldehydes. Products with S configuration were obtained when thiazoline‐containing tertiary alcohol ligands were used as catalysts. The primary alcohol induced corresponding products with R configuration in 68% enantiomeric excess, which was a higher value relative to other N―O ligands possessing a primary alcohol unit in the literature. Furthermore, a plausible transition state model was proposed to explain the observed enantioselectivities. Copyright © 2012 John Wiley & Sons, Ltd.     

一些含氮杂环的脱氢松香酸甲酯衍生物的合成

以歧化松香为原料,将其纯化得到脱氢松香酸,用硫酸二甲酯酯化后,通过12位溴代、7位氧化、脱异丙基硝化等步骤,得到了3个重要的中间体.该3个中间体分别经过亲核取代、还原关环反应后,得到了一些脱氢松香酸甲酯含氮杂环衍生物;产物结构经红外光谱、核磁共振谱、质谱和元素分析进行了表征.     

2-吲哚基噁唑啉和噻唑啉衍生物的合成及生物活性研究

合成了一系列新颖的2-吲哚基噁唑啉和噻唑啉化合物, 它们的结构经IR, 1H NMR, MS和元素分析确认, 同时测试了它们的生物活性. 初步实验结果表明, 对各种植物真菌均有不同程度的抑制活性, 噻唑啉化合物要优于噁唑啉, 其中2a和2b在50 mg/L时, 对茄棉疫, 油菜菌核和芦笋茎枯呈现出100%的抑制率.     

Some Novel Thiazoline and Thiazolidinone Derivatives Surmounted on Substituted Pyrazole Moieties as Potential Antipyretic Agents

Six novel series of substituted thiazoline (V, VI, VII and VIII) and thiazolidinone derivatives (IX and X) resulting from 2,3-dihydro-1, 5-dimethyl-3-oxo-2-phenyl-1H-pyrazole-4-carbaldehyde (I) and 1-phenyl-3-p-tolyl-1H-pyrazolc-4-carbaldehyde (II) were synthesized. The course of this synthesis included the preparation of two new scries of disubstituted thiosemicarbazone precursors (III and IV) which were cyclized with phenacyl bromide, ethyl 2-chloroacetoacetate as well as ethyl bromoacetatc to afford the target thiazolines and thiazolidinoncs. The antipyretic activity of some representative compounds was performed.     

噻唑啉类化合物的合成和抑菌活性

噻唑啉类化合物的合成和抑菌活性;噻唑啉; 合成; 杀菌活性     

One‐Step Synthesis of 2‐Aminothiazoline Derivatives Free of Lachrymatory Intermediates

A convenient one‐step condensation of p‐R‐acetophenones, dioxane dibromide, and N,N′ dialkylthioureas was developed as a synthetic access to derivatives of 2‐amino‐1,3‐thiazoline, such as N‐[4‐(4‐R‐phenyl)‐3‐R1‐2,3‐dihydro‐1,3‐thiazol‐2‐yliden]‐N‐(R1)amine, where R=H, Br, NO₂, or CH₃O, and R1=CH₃, CH₃CH₂, CH₃CH₂CH₂CH₂, or Ph. Unlike the routine syntheses of similar compounds based on lachrymatory ω‐halogenated acetophenones, the one‐step approach escapes the preparation and dealing with inconvenient starting materials. The yields based on the starting p‐R‐acetophenones were in the range of 57–70%.     

STUDIES ON THIAZOLOPYRIDINES. PART 5: SYNTHESIS OF HITHERTO UNKNOWN THIAZOLINONE AND THIAZOLO[3,2-a]PYRIDINE DERIVATIVES HAVING IN THEIR STRUCTURE THE MORPHOLIN-4-YL MOIETY

Condensation of thiazolinone 1 with benzaldehydes 2a, b in ethanolic piperidine afforded the methylidene derivatives 3a, b. Cyclocondensation of compound 3b with malononitrile furnished the novel thiazolo[3,2-a]-pyridine 5. Also, compound 3b was condensed with dimethylformamide-dimethylacetal (DMF-DMA) and triethylortho-formate to yield N,N-dimethylamino 6 and ethoxymethylene 7 derivatives respectively. The novel thiazolo[3,2-a]pyridines 10a, b were obtained by cyclocondensation of compounds 3a, b with benzylidene-malononitriles 8a, b. Similarly, cyclocondensation of compound 3b with benzylidenemalononitrile 11 afforded the thiazolopyridines 12a–c. Ternary condensation of compound (12), 4-morpholinobenzaldehyde 2b and malononitrile (1:1:1 molar ratio) produced the thiazolopyridines 14a–c. When compound 10b was subjected to react with malononitrile in dioxane/piperidine under reflux the novel condensed heterocyclic system 18 was obtained. Treatment of ortho-aminocarbonitrile 10b with formic acid, aromatic aldehyde and triethylorthoformate furnished the thiazolo[2′,3′:1,6] pyrido[2,3-d] pyrimidine 20, azomethine 21a, b and ethoxymethylene 22 derivatives respectively. The structure of the synthesized compounds was established by analytical and spectral data.