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1.
α-Thiotetronic Acids, I: Synthesis and Properties of γ-Alkylidene α-Thiotetronic Acids We report on the synthesis of the alkylidene α-thiotetronic acids 11 and 12a and a variety of their derivatives, starting with 2,3-dimethoxysuccinic thioanhydride ( 4 ) or diethyl 3-thioxoglutarate. The rhodium(II)-catalysed decomposition of the diazoketone 26 furnishes the reductone 12p and the aminoreductone 12r with the thietanone 27 as one of the by-products. 相似文献
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Dithio and Thiono Esters, LVII: Synthesis of Dithio and Thiono Esters of N-Protected β- and γ-Amino Acids The N-Protected β-aminonitriles 1 were transformed into the imidoester or thiolimidoester hydrochlorides 2 or 3 according to Pinner and sulfhydrolyzed with H2S to give the N-protected β-amino thiono esters 4 or dithio esters 5 . Alkylation of the amides 6 and thioamides 7 yields the iminium salts 8/9 and their sulfhydrolysis again 4/5 . By the first approach N-protected γ-amino nitriles 11 were converted into the γ-amino thiono esters 14 and dithio esters 15 . 相似文献
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Heterocyclisations of Ascorbic Acids with α, β-Unsaturated Aldehydes and Ketones, II: Michael Reactions of Ascorbic Acids with Acrolein Derivatives - Structural and Physicochemical Behaviour. The Michael reaction of ascorbic acids ( la – d ) with acrolein ( 2 ) and some derivatives ( 7 , 8 ) is reported. The pH-optimum of the reaction course is 4. Furthermore, solvents supporting ionisation are favourable. α- and β-subsituted acrolein derivatives react differently: Crotonaldehyde, a β-substituted derivative, reacts nearly quantitatively to the spiro compounds 3e and 3f , whereas α-ethyl-acrolein favours the formation of 4g and 4h . 相似文献
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Bicyclic α-Amino Acids, IV: Synthesis of 3-(L1,2,3,4-Tetrahydro-l-naphthalenyl)- and 3-(5,6,7,8-Tetrahydro-5-quinolinyl)alanine The title compounds 1a , b are prepared by Strecker synthesis with the aldehydes 7a , b which are available from 2a , b . The structures of 1a , b and the configurations of the isomeric nitriles 3a , b / 4a , b were elucidated by 1H- and 13C-NMR spectroscopy. 相似文献
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Bicyclic α-Amino Acids, II. On the Preparation of 3-(1-Tetralyl)-and 3-[5-(5,6,7,8-Tetrahydro)quinolyl]alanine Carbonyl olefination of the tetralones 4 does not yield the expected compounds 6 but the isomeric acetic acid derivatives 7 with endocyclic double bond, from which the ketoesters 10 can be prepared via intermediates 8 and 9 . Saponification of 9 and 10 fails to yield the α-ketoacids 11 and 12 . 相似文献
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Bicyclic α-Amino Acids, III: On the Preparation of 2-(1,2,3,4-Tetrahydronaphthalen-1-yl)- and 2-(5,6,7,8-Tetrahydroquinoline-5yl-)glycine Attempted halogenation of 2 does not yield the expected bromo(1,2,3,4-tetrahydronaphthalen-1-yl)acetic acid 4 but the cyclic ketone 3 . The α-ketoesters 5 can be decarbonylated to yield the substituted malonic esters 6 . Compounds 6a and 7a react with isopropyl nitrite to yield the oximinocarboxylic acid 8a which can be hydrogenated at room temperature to yield the title compound 9a . Hydrogenation at 80° C leads to the decalylamino acid 10a . The analogous sequence of reactions ( 6b and 7b→8b→9b ) fails to yield tetrahydroquinolinylglycine 9b . 相似文献
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Dithio and Thiono Esters, LIV: Attempted Synthesis of α-Amino Dithio Esters by the Bislactim Ether Method Sulfhydrolysis of 2,5-bis(methylthio)-3,6-dihydropyrazine ( 5 ) gives rise to 2,5-piperazinedithione ( 8 ) and not to glycine dithiomethylester ( 6 ). The iminium salts 9 , obtained by alkylation of 5, add H2S to form the 1,4-dialkyl 2,5-piperazinedithiones 10 . 5 reacts with methyl chloroformate to give 2,5-bis(methylthio)-pyrazine ( 11 ), and with acetic anhydride to give the 1,4-dihydropyrazine 12 . Sulfhydrolysis of the 6-membered and 7-membered iminium salts 14 leads to the thiolactames 15 . 相似文献
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Nitroketeneaminals, IX: Reaction of α,β-Unsaturated Aldehydes with Nitroketeneaminals Reaction of α,β-unsaturated aldehydes 1a , b with nitroketeneaminal 2a in boiling acetic acid leads to 2-amino-3-nitropyridines 4 unsubstituted at C-6. By refluxing 1a and 2a in alcohol/acetic acid or in alcohols, respectively, 2-alkoxy-1,2,3,4-tetrahydropyridines 7a and 8a are obtained. The reaction of 1a and 2b yields 5-alkoxy-2,3,4,5,6,7-hexahydroimidazo[1,2-a]pyridines 7b and 8b . By 1H-NMR spectroscopy the relative configuration of 7aC, 7aT, 7bC , and 7bT can be determined. 相似文献
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Dimerisation of α-Piperidinoacetonitrile in the Reaction with n-Butylmagnesium chloride The reaction mechanisms which determine the course of the reaction between t- and n-butyl-magnesium chloride and α-piperidinoacetonitrile, have been studied. The formation of different quantities of the reaction products 3-amino-2,4-dipiperidinocrotononitrile and butyl-α-piperidinomethylketone can be explained on the basis of steric hindrace and also through the difference of nucleophilic activity of t- and n-butyl groups. 相似文献
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Thiono and Dithio Esters, XLVIII: α,β-Unsaturated Thio Esters in Diels-Alder Reactions and Michael Additions The reaction of cinnamic acid thio esters with different dienophiles leads to the formation of the Diels-Alder products 3 – 8 ; with lithium enolates the Michael adducts 11 and 13 were isolated. 相似文献
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Reactions of α-Haloamines with Organomagnesium Compounds N,N-Dialkyl-1,2-diaryl-ethylamines 3 can be synthesized from dialkyl-[α-chlorobenzyl]-amines 2 and benzylmagnesium chloride. From allylmagnesium bromide and α-haloamines the γ,δ-unsaturated amines 4 or 9 are formed. These can be converted to γ-chloroamines like 5 or 10 by hydrogen chloride addition. Treatment of dialkyl-[α-chlorbenzyl]-amines 2 with magnesium powder in tetrahydrofuran yields symmetrical diamino-diphenyl-ethanes 11 . From 2d and t-butylmagnesium chloride formation of N-[4-methyl-benzyl]-piperidine ( 12 ) takes place probably via hydride transfer. 相似文献
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1,3-Thiazines XXXI1): 3-(Hydrazinocarbonylthio)propionic Acids from Hydrazine Derivatives, Carbon Oxide Sulfide and β-Propiolactones Hydrazine, N-mono- and N,N-disubstituted hydrazines, N-aminoheterocycles and N-4-phenylthio-semicarbazide were reacted with carbon oxide sulfide and triethylamine to yield the unstable hydrazinecarbothioates 3 , which were 2-ethoxycarbonylated with β-propiolactones to give the novel pharmacologically active (hydrazinocarbonylthio)propionic acids 4 . 相似文献
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H. Stamm 《Archiv der Pharmazie》1971,304(8):567-574
Reactions with Aziridines According to the method of nucleophilic ring opening of intermediately protonated aziridine bases by lithium derivatives of malonic esters in the presence of LiJ and an excess of ester in boiling arenes, some unsubstituted and monosubstituted β-ketoesters 2 and 4 have been aminoethylated by N-substituted aziridines 1 followed by rapid intramolecular cyclization to yield the corresponding 3-acyl-2-pyrrolidones 3 and 6 . Cyclization of the primary aminoethylated products can be prevented by bulky N-substituents. Cyclopentanone and cyclohexanone carboxylic acid esters yield the corresponding spiro compounds 6 . Acidic hydrolysis cleaves the lactam, alkaline hydrolysis the cyclopentanone ring of the 1,6-dioxo-1-azaspiro[4,4]nonane 6a . The analogous 1-o-tolyl substituted spiro compound 6c is a crystalline mixture of probably diastereomeric nature. 相似文献
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Azaindol-Derivatives I: Asymmetric Synthesis of a New α-Amino Acid Starting with the alcohol 4 , a synthesis of racem. 8-azatryptophane 1 and an asymmetric synthesis of its enantiomers 1a and 1b are described: 1a and 1b , prepared from the chiral dihydropyrazines 10a or 10b , are obtained stereoselectively (ee > 95 %). 相似文献
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Asymmetric Electrophilic α-Amidoalkylation, 4): Generation and Trapping Reactions of Chiral N- Acylpyrrolidiniumions The pyrrole derivatives 1 , 6 , and 10 react in the presence of TiCl4 with the silyl enol ether 3 to form α-substituted pyrrolidine amides steroselectively. 6 and 10 (after HCl-addition = > 11 ) react even at ?78°C, the reaction of 10 exceeds that of 6 in yield and stereoselectivity. 相似文献
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August W. Frahm 《Archiv der Pharmazie》1985,318(11):1009-1015
Stereochemistry of Substituted Glutaric Acids, I: (±)-threo- and erythro-2-methyl-3-phenylglutaric Acids Syntheses of (±)-threo-and erythro-2-methyl-3-phenylglutaric acids ( 5,6 ) via the (±)-threo- and erythro-2-phenylbutane-1,1,3-tricarboxylic acids ( 3, 4 ) is described. The configurations of the products were determined. 相似文献