R-四氢噻唑-2-硫酮-4-羧酸二聚反应的量子化学研究

R-四氢噻唑-2-硫酮-4-羧酸反应得到有光学活性的二聚体酰胺双四氢噻唑-2-硫酮并二氧代氢化吡嗪,用半经验量子化学PM3方法研究了反应物、中间产物和二聚体的电子结构.     

（R）—N—乙酰四氢噻唑—2—硫酮—4—羧酸与醇的反应

（Ｒ）－Ｎ－乙酰四氢噻唑－２－硫酮－４－羧酸与醇反应，在ＳＯＣｌ２存在下得到乙酸酯及四氢噻唑－２－硫酮－４－羧酸酯；在碳酸钾存在下得到乙酸酯及四氢噻唑－２－硫酮－４－羧酸；在二环己基碳二亚胺（ＤＣＣ）存在下得到缩水产物Ｎ－乙酰四氢噻唑－２－硫酮－４－羧酸酯。     

(R)-2-硫代四氢噻唑-4-羧酸及其酯的合成

L-半胱氨酸盐酸盐与二硫化碳, 氢氧化钠在硝酸铅存在下进行成环反应得到(R)-四氢噻唑-2-硫酮-4-羧酸产率76% , 后者与 醇在硫酸铁水合物催化下反应得到(R)-四氢噻唑-2-硫酮-4-羧酸酯, 产率40～82% .     

（R）—N—（γ—烃基—δ—酮己酰基）四氢噻唑—2—硫酮—4—羧酸乙酯的合成及…

γ－甲基－δ酮己酸，γ－异丙基－δ－酮己酸在碘化Ｎ－甲基－２－氯吡啶盐存在下分别用（Ｒ）－四氢噻唑－２－硫酮－４－羧酸乙酯反应，得到光学活性的（Ｒ）－Ｎ－（γ－甲基－δ－酮己酰基）四氢噻唑－２硫酮－４羧酸乙酯（ｌａ）及光学活性的（Ｒ）－Ｎ－（γ－异丙基－δ－酮己酰基）四氢噻唑－２－硫酮－４－羧酸乙酯（１ｂ），ｌａ，ｌｂ分别同（Ｒ，Ｓ）－α－苯乙胺反应得到光学活性的酰胺２ａ，２ｂ，同时使（Ｒ，Ｓ）＝     

N—烃氧丙酰基四氢噻唑—2—硫酮的合成

在三聚氯氰存在下由烃氧丙酸与四氢噻唑-2-硫酮反应得到N-烃氧丙酰四氢噻哇-2-硫酮(2a-i),由2a,c-h与格氏试剂反应得到烃氧乙基苯基酮(3a,c-h).产物2a-i未见报道.     

(R)-N-乙酰四氢噻唑-2-硫酮-4-羧酸的合成和量子化学研究

（R）－N－乙酰四氢噻唑－2－硫酮－4－羧酸在三乙胺存在下同乙酰氯反应得到光学活性产物（R）－N－乙酰四氢噻唑－2－硫酮－4－羧酸．用半经验的量子化学方法研究反应物及产物的电子结构和反应热焓．     

α-溴代丙酰氯空间效应的量子化学研究

丙酰氯同四氢噻唑２硫酮及（Ｒ）四氢噻唑２硫酮４羧酸乙酯反应生成Ｎ酰基四氢噻唑２硫酮２ａ及光学活性Ｎ酰基（Ｒ）四氢噻唑２硫酮４羧酸乙酯２ｂ，而α溴代丙酰氯分别同四氢噻唑２硫酮及（Ｒ）四氢噻唑２硫酮４羧酸乙酯反应得到四氢噻唑２α溴代丙酰硫酯３ａ及光学活性４乙氧羰基四氢噻唑２α溴代丙酰硫酯３ｂ．用半经验的量子化学ＰＭ３方法研究了反应物和产物的电子结构和反应的焓变，得到了反应物１ａ异构化的过渡态．     

（R）－N－（γ－烃基－δ－酮己酰基）四氢噻唑－2－硫酮－4－羧酸乙酯的合成及其同（R，S）－α－苯乙胺的反应

γ－甲基－δ－酮己酸，γ－异丙基－δ－酮己酸在碘化Ｎ－甲基－２－氯吡啶盐存在下分别同（Ｒ）－四氢噻唑－２－硫酮－４－羧酸乙酯反应，得到光学活性的（Ｒ）－Ｎ－（γ－甲基－δ－酮己酰基）四氢噻唑－２－硫酮－４－羧酸乙酯（１ａ）及光学活性的（Ｒ）－Ｎ－（γ－异丙基－δ－酮己酰基）四氢噻唑－２－硫酮－４－羧酸乙酯（１ｂ）。１ａ，１ｂ分别同（Ｒ，Ｓ）－α－苯乙胺反应得到光学活性的酰胺２ａ，２ｂ，同时使（Ｒ，Ｓ）－α－苯乙胺拆分，得到光学活性的α－苯乙胺。     

R—四氢噻唑—2—硫酮—4—羧酸同R.S—氨基醇的手性识别反应

Ｒ－四氢噻唑－２－硫酮－４－羧酸同Ｒ．Ｓ－亮氨醇、Ｒ．Ｓ－蛋氨醇、Ｒ．Ｓ－苯丙氨醇和Ｒ．Ｓ－色氨醇反应分别得到光学活性非对映体过剩的铵盐；Ｒ－四氢噻唑－２－硫酮－４－羧酸．Ｓ－色氨醇，同时分离出光学活性对映体过剩的Ｒ－亮氨醇，Ｓ－氨蛋醇，Ｓ－苯丙氨醇及Ｒ－色氨醇，用半经验的量子化学ＰＭ３方法研究了氨基醇的最优构型和电子结构，得到了铵盐的最优几何构型。     

α—溴代丙酰氯与四氢噻唑—2—硫酮衍生物的反应及量化学研究

α－溴代丙酰氯分别同四氢噻唑－２－硫酮及－四氢噻唑－２－硫酮－４－羧酸乙酯反应得四氢噻唑－２－－α－溴代丙酰硫酯２ａ及光学活性－４－乙氧羰基四氢噻唑－２－α溴代丙酰硫酯２ｂ。     

柱前衍生高效液相色谱法测定NTCA的光学纯度

用1-萘胺对乙酰四氢噻唑-2-硫酮-4-羧酸进行柱前衍生,产生非对映体衍生物.以正己烷和乙醇或异丙醇为流动相,选择Chiralcel OD-H色谱柱上对NTCA衍生物进行了拆分,考察了流动相组成和柱温对其衍生物分离的影响,获得较好的分析条件,分离因子达到1.3.该结果进一步与旋光仪法相比较,相对偏差不超过1.9%.     

Synthesis of substituted 4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines and 4-oxo-3,4-dihydroquinazoline-2-thioles

We have developed a liquid-phase synthesis of combinatorial libraries of new disubstituted 4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines and trisubstituted 4-oxo-3,4-dihydroquinazoline-2-thioles. The former were prepared using two general procedures: (i) cyclization of substituted methyl anthranilates with isothiocyanates, or (ii) cyclization of substituted 2-(methylcarboxy)benzeneisothiocyanates with primary amines or hydrazines. 4-Oxo-3,4-dihydroquinazoline-2-thioles were prepared by S-alkylation of disubstituted 4-oxo-2-thioxo-1,2,3,4-tetrahydroquinazolines with alkyl or aryl halides. The hydrolysis of methyl benzimidazo[1,2-c]quinazoline-6(5H)-thione-3-carboxylate led to the corresponding acid. This acid was utilized in the synthesis of new benzimidazo[1,2-c]quinazoline-6(5H)-thione-3-carboxamide and S-substituted 6-mecaptobenzimidazo[1,2-c]quinazoline-3-carboxamide libraries.     

Zur Koordinationschemie des 1,3-Dithiol-2-thion-4,5-diselenolats (dsit) – ein Vergleich mit 1,3-Dithiol-2-thion-4,5-dithiolat (dmit)

Coordination Chemistry of 1,3-Dithiole-2-thione-4,5-diselenolate (dsit) — Comparison with 1,3-Dithiole-2-thione-4,5-dithiolate (dmit) Synthesis and properties of metal(II) and/or metal(III) bis-chelates of 1,3-dithiole-2-thione-4,5-diselenolate (dsit) of general type (Bu₄N)_n[M(dsit)₂] (n = 2: M ? Zn, Cd, Hg, Cu, Ni, Pd, Pt; n = 1: M ? Ni, Au) are described. By comparison of the ir, ¹³C nmr, epr spectra, cyclovoltammetric data, and x-ray investigations (nickel-bis-chelates) of chelates of dsit and those of the chelates of 1,3-dithiole-2-thione-4,5-dithiolate (dmit) the consequences of selenium for sulfur substitution on position 4 and 5 of the heterocyclic ligand are discussed.     

Enantioselective synthesis of both enantiomers of the neuroexcitant 2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA)

The preparation of both enantiomers of 2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA), 1, an analogue of the neuroexcitant 2-amino-3-(3-hydroxy-5-methyl-4-yl) propanoic acid (AMPA) is described. The enantiomerically pure glycine derivative tert-butoxycarbonyl-2-(tert-butyl)-3-methyl-4-oxo-1-imidazolidinecarboxylate (BOC-BMI) was coupled with 4-bromomethyl-2-methoxymethyl-5-tert-butylisoxazolin-3-one 6 to give the intermediates (2R,5R)-8 and (2S,5S)-8. These alkylated products were hydrolyzed under mild conditions to give enantiopure (R)-1 and (S)-1 with e.e.'s in excess of 99% in 33% overall yield.     

Zur Koordinationschemie des 1,3-Thiaselenol-2-thion-4,5-dithiolats (dmits) – ein Vergleich mit 1,3-Dithiol-2-thion-4,5-dithiolat (dmit)

Coordination Chemistry of 1,3-Thiaselenole-2-thione-4,5-dithiolate (dmits) – Comparison with 1,3-Dithiole-2-thione-4,5-dithiolate (dmit) Synthesis and properties of metal(II) and/or metal(III)-bis-chelates of 1,3-thiaselenole-2-thione-4,5-dithiolate (dmits) of the general type (Bu₄N)_n[M(dmits)₂] (n = 2: M = Zn, Cd, Hg, Ni, Cu, Pd; n = 1: M = Au, Ni) are described. By comparison of the i.r., ¹³C-n.m.r., epr spectra and cyclovoltammetric data of chelates of dmits and those of 1,3-dithiole-2-thione-4,5-dithiolate (dmit) the consequences of the substitution of selenium for sulfur on position 3 of the heterocyclic ligand dmit are discussed.     

Preparation of both enantiomers of malic and citramalic acid and other hydroxysuccinic acid derivatives by stereospecific hydrations of cis or trans 2-butene-1,4-dioic acids with resting cells of Clostridium formicoaceticum

(R)-Malic, (S)-malic, (R)citramalic, (S)-citramalic, (2R,3S)-2-hydroxy-3-methyl-succinic and (2R,3S)-2,3-dimethyl-2-hydroxysuccinic acid were prepared on scales up to 25 mmol by stereospecific addition of water to different 2-butene-1,4-dioic acid derivatives catalyzed by resting cells of Clostridium formicoaceticum (Scheme 1). The (3R)-monodeuterio (R)- and (S)-malic acid as well as (R)- and (S)-citramalic acid were prepared using freeze-dried cells in ²H₂O-buffer. The stereochemical purity of the products was in most cases ≥ 99%.     

Synthesis of four enantiomerically pure 4-(4-carbamoyl-1,2,3-triazol-1-yl)-2,3-dihydroxy-1-methoxybutylphosphonic acids

CuCl-catalysed cycloaddition of methyl propiolate to O,O-diisopropyl (1S,2R,3S)- and (1R,2R,3S)-, or O,O-dibenzyl (1S,2R,3S)-, (1R,2R,3S)-, (1S,2R,3R)- and (1R,2R,3R)-4-azido-1,2,3-trihydroxy-2,3-O-isopropylidenebutylphosphonates followed by methylation of HO–C-1, ammonolysis of methoxycarbonyl groups and hydrolysis of isopropylidene acetals led to diisopropyl (1S,2R,3S)- and (1R,2R,3S)-4-(4-carbamoyl-1,2,3-triazol-1-yl)-2,3-dihydroxy-1-methoxybutylphosphonates or, after hydrogenolytic removal of benzyl groups, to (1S,2R,3S)-, (1R,2R,3S)-, (1S,2R,3R)- and (1R,2R,3R)-4-(4-carbamoyl-1,2,3-triazol-1-yl)-2,3-dihydroxy-1-methoxybutylphosphonic acids.     

Stereoselectivities in AgBF4-catalyzed and photoinduced phenyl-rearrangement of 2-chloropropiophenone

(S)-2-Phenylpropionic acid was stereoselectively obtained by the AgBF₄-catalyzed phenyl-rearrangement of (S)-2-chloropropiophenone dimethyl acetal, while the photoirradiation of (S)- or (R)-2-chloropropiophenone afforded partially racemized (S)- or (R)-2-phenylpropionic acid, respectively. An intramolecular S_N2 mechanism is suggested for the former rearrangement. The latter result is indicative of the intervention of an ion or radical intermediate in the photoinduced phenyl-rearrangement.     

Crystallographic and ab initio theoretical studies of (2R,3R)-1-methyl-5-oxo-2-phenyltetrahydro-1H-pyrrole-3-carboxylic acid. The comparison of chiral (I) and racemic (II) structure

Crystal and molecular structures of (2R,3R)-1-methyl-5-oxo-2-phenyltetrahydro-1H-pyrrole-3-carboxylic acid (I) and (2R^*,3R^*)-1-methyl-5-oxo-2-phenyltetrahydro-1H-pyrrole-3-carboxylic acid (II) are presented. The alternative packings were studied using ab initio quantum-chemical methods. Energies of hydrogen bonds for real and model cases are discussed. Infinite chains of molecules instead of carboxylic acid dimers were observed.     

Isolation, structure, and synthesis of dolastatin D, a cytotoxic cyclic depsipeptide from the sea gare Dolabella auricularia

Dolastatin D (1), a cytotoxic cyclic depsipeptide possessing the novel β-amino acid (2R,3R)-3-amino-2-methylbutanoic acid [(2R,3R]-3] as a component, has been isolated from the Japanese sea hare Dolabella auricularia. The absolute stereostructure of 1 was elucidated on the basis of spectroscopic analysis and chemical degradation and was further confirmed by synthesis.