Condensation of 2, 2 -dinitro-1, 3-peopanediol with hydrazineacetic acid esters

Conclusions The condensation of 2, 2-dinitro-1, 3-propanediol with pyrazineacetic acid esters leads to the formation of the esters of 4, 4-dinitropyrazolidine-2-acetic acid, which are spontaneously converted to the esters of 4-nitropyrazole-1-acetic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2333–2334, October, 1972.     

Heck-mediated synthesis and photochemically induced cyclization of [2-(2-styrylphenyl)ethyl]carbamic acid ethyl esters and 2-styryl-benzoic acid methyl esters: total synthesis of naphtho[2,1f]isoquinolines (2-azachrysenes)

We describe two new closely related total syntheses of naphtho[2,1-f]isoquinolines. The first synthesis consists of a Heck coupling reaction between trifluoromethanesulfonic acid 2-(2-ethoxycarbonylaminoethyl)phenyl esters and styrenes to give [2-(2-styrylphenyl)ethyl]carbamic acid ethyl esters. These compounds cyclize to give (2-phenanthren-1-yl-ethyl)carbamic acid ethyl esters, from which 2-azachrysenes can be obtained in a three-step sequence. The second synthesis includes a new total synthesis of 2-styrylbenzoic acid methyl esters by Heck coupling of methyl o-iodobenzoates to styrenes, followed by the transformation of the resulting benzoic acid derivatives into phenanthrene-1-carboxylic acid methyl esters and then into the target compounds by a six-step sequence including a Bischler-Napieralski cyclization.     

Synthesis of five-membered 2-heteroaryl 2-heteroaromatic carboxylates and attempted cyclization to bisheteroaryl[2,3-b:3′,2′-d]pyran-2-one

2-Heteroaryl 2-heteroaromatic carboxylates were prepared by reactions of 2-heteroaromatic carbonyl chlorides and 2(5H)-furanone, 2(5H)-thiophenone, and 1-methyl-2(5H)-pyrrolone in triethylamine. The ¹H nmr spectra of the esters showed that the electronic effect of both heteroaromatic rings did not cause any sizable shift from each other except for 1-methyl-2-pyrrolyl 1-methyl-2-pyrrolecarboxylate ( 5c ). Attempts to cyclize the esters to heteroaryl-fused pyran-2-ones were unsuccessful. The results may be explained by the most stable conformation of the esters in which two heteroatoms are anti along the C? 0 bond of the ester group.     

Reaction of organozinc reagents formed in reaction of dibromomalonic acid dialkyl esters and zinc, with 2-arylmethylenemalonic acid dinitriles and 3-aryl-2-cyanopropenoic acid methyl esters

Organozinc compounds, obtained from dibromomalonic acid dialkyl esters and zinc, react with 2-arylmethylmalonic acid dinitriles and 3-aryl-2-cyanopropenoic acid methyl esters forming 3-aryl-2,2-dicyanocyclopropane-1,1-dicarboxylic acid dialkyl esters and 3-aryl-2-cyanocyclopropane-1,1,2-tricarboxylic acid trimethyl esters. ¹H and ¹³C NMR, ³ J _CH constants are considered.     

Reduction of 3-substituted 2-methylquinolines with sodium tetrahydroborate

Reduction of esters of 2-metylquinoline-3-carboxylic acids and their perchlorates gave esters of 1,4-dihydro-2-methylquinoline-3-carboxylates, while derivatives of 1,2-dihydroquinoline were formed in the case of 1,2-dimethyl-3-ethoxycarbonyl-7-methoxyquinolinium perchlorate. Reduction of esters of 2-methylquinoline-3-carboxylic acid, 1,2-dimethyl-3-ethoxycarbonyl-1-methoxyquinolinium perchlorate and 3-acetyl-2-methyl-quinoline with sodium tetrahydroborate in acetic acid gave esters of 1,2-dimethyl- and 2-methyl-1,2,3,4-tetrahydroquinoline-3-carboxylic acid and 3-acetyl-2-methyl-1,2,3,4-tetrahydroquinoline.Latvian Institute of Organic Synthesis, Riga, LV-1006. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1383–1390, October, 1996. Original article submitted October 11, 1995.     

Preparation of single-enantiomer semiochemicals using 2-methoxy-2-(1-naphthyl)propionic acid and 2-methoxy-2-(9-phenanthryl)propionic acid

Enantioresolution of 3-octanol, 6-methyl-5-hepten-2-ol (sulcatol), and 1-octen-3-ol was conducted using (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid (MαNP acid) and (S)-(+)-2-methoxy-2-(9-phenanthryl)propionic acid (M9PP acid). In each case, the diastereomeric esters obtained were readily separated by HPLC. The stereochemistry of the esters could be assigned from their respective ¹H NMR analyses. Solvolyses of the esters gave enantiopure alcohols and acids. MαNP and M9PP acids displayed almost equivalent properties in ¹H NMR anisotropy. The chiral resolving ability of M9PP acid was slightly superior to that of MαNP acid in HPLC.     

Chlorination of tetrahydrofuran-2-carboxylic acid esters

The photochemical chlorinatlon of tetrahydrofuran-2-carboxylic acid esters with chlorine at –15 to –20C leads primarily to the formation of 5-chlorotetrahydrofuran-2-carboxylic acid esters (70–80%). 4,5-Dihydrofuran-2-carboxylic acid and furan-2- carboxylic acid esters are formed as side products. The structures of the principal and side products were investigated by PMR and mass spectroscopy.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 166–168, February, 1979.     

Catalytic method for obtaining 2-aryl-substituted imidazolines

2-Arylimidazolines were synthesized catalytically on KU-2 ion-exchange resin by condensation of esters of aromatic acids (benzoic, phenylacetic, anthranilic, salicylic, and 3,5-di-tert-butylsalicylic) with ethylenediamine. From 30 to 48% of the diamide is formed in addition to the corresponding imidazolines in the condensation of the esters of benzoic and phenylacetic acids with ethylenediamine. The condensation of the esters of salicylic and 3,5-di-tert-butylsalicylic acids with ethylenediamine gave quantitative yields of the monoamide, which is dehydrated to 2-arylimidazoline during vacuum distillation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 383–385, March, 1972.     

A study of the tautomerism of the N-butyl-4(2)-methoxycarbonyl-pyrrolid-3-ones and their hydrochlorides

The tautomerism of N-butyl-2-methoxycarbonyl-4-methylpyrrolid-3-one (I), N-butyl-4-methoxycarbonylpyrrolid-3-one (II), N-butyl-4-methoxycarbonyl-2-methylpyrrolid-3-one (III), N-butyl-4-methoxycarbonylpyrrolid-3-one hydrochloride (IV), and N-butyl-4-methoxy-carbonyl-2-methylpyrrolid-3-one hydrochloride (V) has been studied by UV and IR spectroscopy. It has been found that the esters I–V are highly ionized in aqueous and ethanolic solutions at concentrations of 10^?2–10^?3 M. On passing from methyl cyclopentran-1-one-2-carboxylate to the esters II and III the position of the equilibrium in heptane and CCl₄ shifts in the direction of the keto form. On passing from the esters II and III to the esters IV and V, the position of the equilibrium shifts in the direction of the enol. Meyer's relationship is not satisfied for the esters II and III, while it is satisfied for the esters IV and V. Hypotheses have been put forward on the causes of the phenomena mentioned.     

A concise synthesis of protected diethyl 1-amino-2-hydroxyalkylphosphonates

An efficient diastereoselective synthesis of 5-substituted (2-thioxo-oxazolidin-4-yl)phosphonic acid diethyl esters from metallated diethyl isothiocyanomethylphosphonate and aldehydes has been developed. The three-step transformation of oxazolidine-2-thione derivatives into N-Boc 1-amino-2-hydroxyalkylphosphonic acid diethyl esters is also described.     

A study of the tautomerism of the N-butyl-4(2)-methoxycarbonyl-pyrrolid-3-ones and their hydrochlorides

The tautomerism of N-butyl-2-methoxycarbonyl-4-methylpyrrolid-3-one (I), N-butyl-4-methoxycarbonylpyrrolid-3-one (II), N-butyl-4-methoxycarbonyl-2-methylpyrrolid-3-one (III), N-butyl-4-methoxycarbonylpyrrolid-3-one hydrochloride (IV), and N-butyl-4-methoxy-carbonyl-2-methylpyrrolid-3-one hydrochloride (V) has been studied by UV and IR spectroscopy. It has been found that the esters I–V are highly ionized in aqueous and ethanolic solutions at concentrations of 10^–2–10^–3 M. On passing from methyl cyclopentran-1-one-2-carboxylate to the esters II and III the position of the equilibrium in heptane and CCl₄ shifts in the direction of the keto form. On passing from the esters II and III to the esters IV and V, the position of the equilibrium shifts in the direction of the enol. Meyer's relationship is not satisfied for the esters II and III, while it is satisfied for the esters IV and V. Hypotheses have been put forward on the causes of the phenomena mentioned.     

Synthesis of homologs of 2-aminoethylphosphonic acid

Conclusions Some homologs of 2-aminoethylphosphonic acid were synthesized by the addition of dialkyl phosphites to nitroolefins and the subsequent reduction of the thus obtained esters of 2-nitroethylphosphonic acid to the amino esters. Hydrolysis of the latter gave the free acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1382–1385, June, 1973.     

Synthesis of 2-oxazolines via boron esters of N-(2-hydroxyethyl) amides

A new, convenient, one-pot process is presented for the synthesis of 2-oxazolines in high yields (75-94%) via boron esters of N-(2-hydroxyethyl) amides. The procedure involves thermolysis of the boron esters at 240-260 °C, in the presence of solid CaO as an acid scavenger and allows the preparation of oxazolines from hydroxyethyl amides of aliphatic and aromatic monocarboxylic acids.     

Reaction of 2-methyl-5-(2′-carbochloroethyl) furan with polyhydric aliphatic alcohols

Summary The reaction of 2-methyl-5-(2-carbochloroethyl)furan with ethylene glycol, diethylene glycol, 1,3-butanediol or glycerol gave the previously unknown furan esters and chloro esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1096–1097, June, 1965     

2-Benzoyl-2-ethoxycarbonylvinyl-1 and 2-benzoylamino-2-methoxy-carbonylvinyl-1 as N-protecting groups in peptide synthesis. Their application in the synthesis of dehydropeptide derivatives containing N-terminal 3-heteroarylamino-2,3-dehydroalanine

Ethyl 2-benzoyl-3-dimethylaminopropenoate ( 6 ) and methyl 2-benzoylamino-3-dimethylaminopropenoate ( 46 ) were used as reagents for the protection of the amino group with 2-benzoyl-2-ethoxycarbonylvinyl-1 and 2-benzoylamino-2-methoxycarbonylvinyl groups in the peptide synthesis. Reactions of ethyl 2-benzoyl-3-dimethylaminopropenoate (6) with α-amino acids gave N-(2-benzoyl-2-ethoxycarbonylvinyl-1)-α-amino acids 13–19. These were coupled with various amino acid esters to form N-(2-benzoyl-2-ethoxycar-bonylvinyl-1)-protected dipeptide esters 20–31. The removal of 2-benzoyl-2-ethoxycarbonylvinyl-1 group, which was achieved by hydrazine monohydrochloride or hydroxylamine hydrochloride, afforded hydrochlo-rides of dipeptide esters 32–41 in high yields. Similarly, the substitution of the dimethylamino group in methyl 2-benzoylamino-3-dimethylaminopropenoate ( 46 ) by glycine gave N-(2-benzoylamino-2-methoxycar-bonylvinyl-1)glycine ( 47 ), which was coupled with glycine ethyl ester to give N-[N-(2-benzoylamino-2-methoxycarbonylvinyl-1)glycyl]glycine ethyl ester ( 48 ). Treatment of 48 with 2-arnino-4,6-dirnethylpyrimi-dine afforded N-[glycyl]glycine ethyl ester hydrochloride (34) in high yield. Amino acid esters and dipeptide esters were employed in the preparation of tri- 58-70, tetra- 71–82, and pentapeptide esters 83–85 containing N-terminal 3-heteroarylamino-2,3-dehydroalanine. 2-Chloro-4,6-dimethoxy-1,3,5-triazine was employed as a coupling reagent for the preparation of peptides 58–85.     

Stossaktivierungsspektren von 2-Alkoxybenzoesäuremethylestern

The CA spectra of the [M – Alkene]⁺·- and [M – Alkyl]⁺- ions from several 2-alkoxy-benzoic acid methyl esters and two 2H labelled 2-ethoxybenzoic acid methyl esters are discussed. The results show that the [M – alkene]⁺· ions decomposing after 10^?5 s by collisional activation have the structure of the ionised salicylic acid methyl ester. Moreover, it is demonstrated that the [M – methyl]⁺ ions from the 2-ethoxy esters exist in two different structures. No equilibration between these two structures is observed even after 10^?5s. Structures for several daughter ions generated by collisional activation are discussed using the CA spectra of the labelled compounds.     

Isomerization of S-2-hydroxyalkyl esters of phosphorus acids

Conclusions Based on the³¹P NMR spectral data, the isomerization of the S-2-hydroxyalkyl esters of thiophosphoric and thiophosphonic acids to the corresponding 2-mercaptoalkyl esters of phosphoric and phosphonic acids proceeds with the formation of stable intermediate compounds, which, in all probability, contain the 1,3,2-thiaoxaphospholane ring. The 2-mercaptoalkyl esters of phosphorus acids decompose to either the dialkylphosphoric or phosphonic acid and alkylene sulfide. Compounds of the 1,3,2-thiaoxaphospholane series are not formed during the decomposition.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2142–2144, September, 1978.     

A simple route to syn α-Amino-β-Hydroxy esters by C-2 regioselective opening of a, β-Epoxy esters with metal halides

α,β-Epoxy esters are opened by NaX (X = I, Br) in a regio and stereoselective fashion to β-hydroxy-α-halo esters, which represent suitable precursors of syn α-amino-β-hydroxy esters and β-hydroxy esters.     

Esterification of carboxylic acid derivatives with 2-fluoro-2,2-dinitroethylsulfuric acid

Conclusions The reaction of carboxylic acid anhydrides, acid halides, esters and salts with 2-fluoro-2,2-dinitroethyl sulfuric acid is a general method for preparing esters of 2-fluoro-2,2-dinitroethanol.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 381–383, February, 1977.     

Electrophilic substitution reactions of esters of 4,5-substituted 1,3-dithiol-2-ylideneacetic and 1,3-dithiol-2-ylidenemalonic acids

The electrophilic substitution reactions (with halogens, POCl₃ + DMF, diazonium salts, iodoso compounds) of both esters of 4,5-substituted 1,3-dithiol-2-ylideneacetic acids and sodium salts of monoethyl esters of the corresponding malonic acids can be used for the synthesis of 2-methylene-1,3-dithiole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 898–900, July, 1989.