Amino acid derivatives that stabilize secondary structures of polypeptides : II. The most stable conformation of peptides containing 3-amino-2-piperidone-6-carboxylic acid (Acp)

From ¹H NMR evidence, the conformation of the piperidone ring of 3-amino-6-carboxyl-2-piperidone (ACP) in the derivatives Ac-Acp-NHET. Cbz-Gly-Acp-OEt, Cbz-Gly-Acp-Gly-OEt, Boc-$\text{L}$-Phe-$\text{LL}$-Acp-$\text{L}$-Ala-OCH₃, and Boc-$\text{L}$-Phe-$\text{DD}$-Acp-$\text{L}$-Ala-OCH₃ is shown to be a chair with the RCONH function equatorially and the CONHR′ function axially disposed. An internal hydrogen bond of the β-turn type is proposed for these amide derivatives.     

Synthesis and biological activities of novel 2-amino-1,3-thiazole-4-carboxylic acid derivatives

A series of novel 2-amino-1, 3-thiazole-4-carboxylic acid derivatives were designed and synthesized. Their structures were confirmed by melting points, IR, ¹H NMR, ¹³C NMR, and HRMS or elemental analysis. Biological activities of all title compounds including fungicidal activity and antivirus activity were evaluated systematically. Preliminary bioassays indicated that these compounds exhibited good fungicidal activity at 50 μg/mL, compounds 4b and 4i exhibited over 50% activity against six fungi tested. Most compounds showed good activity against TMV with different models in vivo at 100 μg/mL. Compounds 4c and 4e stood out with high effects against TMV in vivo in all models tested, including protective, inactivative, curative, and inductive activities. These data demonstrate a new strategy for fungi and virus control.     

Asymmetric synthesis of 2-amino-3-hydroxynorbornene-2-carboxylic acid derivatives

The enantioselective synthesis of 2-amino-3-hydroxynorbornene-2-carboxylic acid derivatives (5) was studied using the Diels-Alder reaction between cyclopentadiene and different dienophiles, i.e., alkyl 5-oxo-2-phenyloxazol-4-methylenecarbonates (1) or 2-benzoylamino-3-alkoxycarbonyloxy-acrylates (12), operating with different Lewis acids and both with thermal and with ultrasound conditions. The enantioselective synthesis of the exo/endo compounds 5c,d and 5'c,d was achieved starting from the chiral menthyl acrylates 12b,c using Mg(ClO(4))(2) as the catalyst and ultrasound. The cycloadducts were obtained in very good yield, in mild conditions, in short time, and in good diastereomeric excess (exo, 80%; endo, 87%). Finally, the use of alkylidene-oxazolones or acrylates and EtAlCl(2) or Mg(ClO(4))(2) as the catalyst allowed control of the cycloaddition reaction in favor of the exo or endo products.     

Synthesis of unnatural amino acids: spiro[4.5]-2-aza-decan-3-carboxylic acid

Spiro[4.n]-2-aza-alkan-carboxylic acids represent bulky proline analogues with increased lipophilicity. They are readily available from cyclic nitriles via alkylation with bromoacetaldehyde acetals, reduction to the corresponding amine, cyclisation to the imine and subsequent Strecker synthesis.     

Polyfunctional imidazoles: VI. Synthesis of 2-amino-1-aryl-4-chloro-1H-imidazole-5-carboxylic acids derivatives

Aryl-2,4-dichloro-5-formylimidazoles by a successive treatment with hydroxylamine and thionyl chloride were converted into 1-aryl-2,4-dichloroimidazole-5-carbonitriles which by the action of sodium azide and tin(II) chloride were transformed into 2-amino-1-aryl-4-chloroimidazole-5-carbonitriles. The consecutive reactions of 2-azido-1-aryl-4-chloro-5-formylimidazoles with N-bromosuccinimide, methanol, or amides led to the formation of methyl esters and amides of 2-azido-1-aryl-4-chloroimidazole-5-carboxylic acids. The reduction of the latter with tin(II) chloride resulted in the corresponding derivatives of 2-amino-1-aryl-4-chloroimidazole-5-carboxylic acids, and the reduction of 2-azido-1-aryl-4-chloroimidazole-5-carboxylic acids was accompanied with decarboxylation and yielded 2-amino-1-aryl-4-chloroimidazoles.     

“一锅法”合成6-氯取代的2-苯氧甲基-3-喹啉甲酸衍生物（英文）

设计了以6-氯-2-氯甲基-3-喹啉甲酸乙酯(1)为起始化合物,在溶剂乙腈、缚酸剂无水碳酸钾的条件下,通过"一锅法"与苯酚及取代苯酚2a-o反应,合成了喹啉环上含有氯原子的6-氯-2-苯氧甲基-3-喹啉甲酸衍生物3a-o.所合成的化合物3a-o的结构经红外光谱、核磁共振氢谱、核磁共振碳谱和高分辨质谱得以证实.     

Synthesis and antitumor evaluation of novel derivatives of 6-amino-2-phenylbenzothiazoles

Novel derivatives of 6-amino-2-phenylbenzothiazole bearing different substituents (amino, dimethylamino or fluoro) on the phenyl ring were prepared as the corresponding hydrochloride salts. 6-Nitro-2-(substituted-phenyl)benzothiazoles (1-6) were synthesized by condensation reactions of substituted benzaldehydes with 2-amino-5-nitrothiophenol. Nitro derivatives were reduced to the amino derivatives with SnCl(2)/HCl.Water soluble hydrochloride salts of 6-amino-2-(substituted-phenyl)benzothiazole (13-19)were prepared using concentrated or gaseous HCl. Compounds 13-19 were found to exert cytostatic activities against malignant human cell lines: cervical (HeLa), breast (MCF-7),colon (CaCo-2), laryngeal carcinoma (Hep-2), and normal human fibroblast cell lines (WI-38).     

Synthesis and biological activity of some new 3-and 6-substituted coumarin amino acid derivatives. Part I

The synthesis of 6-nitrocouarrain-3-CO-amino acids and their corresponding methyl esters (II-XVII) and some dipeptide methyl esters (XVIII-XXVI) are described. 6-(N-Tosyl- or N-phthalylaminoacyl)aminocoumarin-3-carboxylic acid methyl esters (XXXIV-XL) and 3-(N-phthalyl- or N-tosylaminoacytyaminocoumarins (XLV-LVI) have been prepared via the carbodiimide and acid chloride methods. Hydrazinolysis of 3- or 6-(N-phthalylaminoacyl)aminocoumarin derivatives in tetraline gave the corresponding 3- and 6-(aminoacyl)aminocoumarins and the carboxylic acid hydrazides (XLI-LVIII), respectively. 3-(N-Tosyl-L-Val-L-Leu-)aminocoumarin (LIX) was synthesized via the azide method. Twenty four of various substituted 3- and 6-aminoacylcoumarin derivatives were found to possess specific antimicrobial activities towards different microorganisms.     

Synthesis of N(N6)-exocyclic amino acid derivatives of 3-phenylisopropylsydnoneimine

The synthesis of N₆-amino acid derivatives of 3-phenylisopropylsydnoneimine of the carbamoyl and acyl types, which were obtained by the method of polymeric activated esters, is described. The structures of the synthesized compounds were confirmed by their IR and UV spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1335–1339, October, 1978.     

Synthesis of unnatural amino acids: (S,S,S)-2-azabicyclo[3.3.0]octane-3-carboxylic acid

(S,S,S)-2-Azabicyclo[3.3.0]octane-3-carboxylic acid 1, a structural element of the very potent ACE inhibitor HOE 498, is readily available via a diastereo selective synthesis starting from serine or cystine.     

Synthesis of methyl esters of 5-amino-4-(substituted amino)-2-methylthio-7H-pyrrolo[2,3d]-pyrimidine-6-carboxylic acids

The optimum route for the synthesis of methyl esters of N-[(4-substituted amino)-5-cyano-2-methylthiopyrimidin-6-yl]amino acids (which are starting materials for preparing the methyl esters of the corresponding 5-amino-4-(substituted amino)pyrrolo[2,3-d]pyrimidine-6-carboxylic acids) is via subsequent reactions of 4,6-dichloro-2-methylthiopyrimidine-5-carbonitrile with amines and methyl glycinate. In some examples, the reaction of methyl N-(4-chloro-2-methylthio-6-pyrimidinyl)aminoacetate with amines occurs to give the corresponding acid amides. The previously unknown synthesized derivatives of pyrimidin-6-yl amino acids and 4,5-diaminopyrrolo[2,3-d]pyrimidine- 6-carboxylic acids possess fungicidal properties.Vilnius University, Vilnius 2006, Lithuania. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 7, pp. 955–961, July, 2000.     

Synthesis and crystal structures of two silver(I) complexes derived from 2-amino-6-methylpyridine with nicotinic acid and isonicotinic acid

The reaction of Ag₂O and 2-amino-6-methylpyridine (AMP) with nicotinic acid (HNA) and isonicotinic acid (HINA), respectively, afforded two silver(I) complexes, [Ag₂(NA)₂(AMP)₂] _n (I) and [Ag₂(INA)₂(AMP)₂] _n (II). Both complexes were characterized by elemental analyses and X-ray single-crystal diffraction. Complex I is a pyridine-3-carboxylate bridged polynuclear silver(I) complex, in which the Ag atom is in a tetrahedral geometry, while complex II is a pyridine-4-carboxylate bridged polynuclear silver(I) complex, in which the Ag atom is in a distorted T-shaped geometry. The crystal of I is monoclinic: space group P2₁/c, a = 8.079(2), b = 17.150(3), c = 8.912(2) Å, β = 98.106(2)°, V = 1222.5(5) ų, Z = 4. The crystal of II is monoclinic: space group P2₁/c, a = 7.225(1), b = 12.049(1), c = 15.053(2) Å, β = 102.050(1)°, V = 1281.6(3) ų, Z = 4.