New deoxygenation reactions of sulfoxides,selenoxides and primary nitroalkanes to sulfides,selenides and nitriles

The title reactions are performed at room temperature for short periods using P₂I₄. The resulting products are formed in particularly high yield.     

Conjugate addition of alkyl groups to α,β-unsaturated sulfoxides via Michael addition of nitroparaffins and subsequent denitration with tributyltin hydride

Michael addition of nitroparaffins to α,β-unsaturated sulfoxides is well effected in the presence of DBU. The nitro group in the adduct is replaced by hydrogen with Bu₃SnH without influence to the sulfinyl function. The overall reations provide an efficient method for the conjugate addition of alkyl groups to α,β-unsaturated sulfoxides.     

Preparation of α,β-dehydro-β-amino acid derivatives by tin-promoted addition of malonates to simple nitriles

Simple aliphatic and aromatic nitriles undergo reaction with malonate esters in the presence of tin(IV) chloride to give derivatives of α,β-dehydro-β-amino acids. The same products are obtained through use of bromomalonate esters.     

An asymmetric synthesis of carboxylic acid derivatives,including lactic acid and α-amino acid derivatives,from optically active 1-chlorovinyl p-tolyl sulfoxides and ester lithium enolates with creation of chirality at the α-position

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides, which were synthesized from symmetrical ketones or methyl formate and (R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with lithium enolate of carboxylic acid tert-butyl esters gave optically active adducts having a substituent (alkyl, alkoxy, or dibenzylamino group) at the α-position with high 1,4-chiral induction from the sulfur chiral center. The adducts were converted to optically active esters, lactic acid, and α-amino acid derivatives having a chiral center at the α-position. When this addition reaction was carried out with an ester enolate generated from excess carboxylic acid tert-butyl ester with LDA in the presence of HMPA, the diastereomer of the adduct was obtained. By using the two reaction conditions for the generation of the ester enolate, a new method for asymmetric synthesis of both enantiomers of carboxylic acid derivatives having a substituent at the α-position from the one chiral source, (R)-(−)-chloromethyl p-tolyl sulfoxide, was achieved.     

Alkylation of carboxylic acid derivatives with dialkoxytitanacyclopropane reagents

Methods for the generation of dialkoxytitanacyclopropanes (dialkoxytitanium olefin complexes) are surveyed. Alkylation of carboxylic acid derivatives with these reagents giving rise to -titanio ketones and related species, which are spontaneously transformed into the corresponding cyclopropane compounds or react with external electrophiles, are considered.     

Enantioselective synthesis of beta-aryl-gamma-amino acid derivatives via Cu-catalyzed asymmetric 1,4-reductions of gamma-phthalimido-substituted alpha,beta-unsaturated carboxylic acid esters

A series of chiral beta-aryl-substituted gamma-amino butyric acid derivatives were synthesized in good enantioselectivities via the Cu-catalyzed asymmetric conjugate reduction of gamma-phthalimido-alpha,beta-unsaturated carboxylic acid esters using Cu(OAc)2 x H2O as a catalyst precursor, (S)-BINAP as a ligand, PMHS as a hydride source, and t-BuOH as an additive. The methodology has been applied successfully to the enantioselective synthesis of a chiral pharmaceutical, (R)-baclofen.     

Highly regio- and stereoselective asymmetric bromoazidation of chiral alpha,beta-unsaturated carboxylic acid derivatives: scope and limitations

Lewis acid catalyzed asymmetric bromoazidation of chiral alpha,beta-unsaturated carboxylic acid derivatives was performed using N-bromosuccinimide (NBS) and trimethylsilyl azide (TMSN3) as the bromine and azide sources. Among the Lewis acids, Yb(OTf)3 was found to be the best catalyst. Regio- and anti-selectivity of 100% and moderate to good diastereoselectivity (up to 89:11) with good yields were obtained when Oppolzer's bornane sultam chiral auxilairy was used. Diastereoselectivity of >95:05 was observed when (2S,5S)-2,5-diphenylpyrrolidine was used as the chiral auxiliary.     

Reaction of o,o-diisopropyl dithiophosphate with nitriles of carboxylic acids

Conclusions The interaction of O,O-diisopropyl dithiophosphate with benzonitrile, phenylacetonitrile, adipodinitrile, and ethyl cyanoacetate proceeds with the formation of unstable imidoyldithiophosphates, which are capable of being rearranged to form the corresponding phosphorylated thioamides. The further course of the reaction is associated with the splitting of the P-N-C or P-S-C bonds in the N-(O,O-diisopropylthiophosphonyl)thioamides and probably of the imidoyldithiophosphates under the action of a second molecule of the dithio acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 861–866, April, 1979.     

Palladium-catalyzed reactions of arylboron compounds with carboxylic acid chlorides

Reactions of sodium tetraarylborates and arylboronic acids with acyl chlorides in the presence of palladium salts afford non-symmetrical ketones in high yields under mild conditions.     

Enantioselective solution- and solid-phase synthesis of glutamic acid derivatives via Michael addition reactions

The enantioselective conjugate addition of Schiff base ester derivatives to Michael acceptors either in solution (56–89% e.e.) or on solid-phase (34–82% e.e.) gave optically active unnatural α-amino acid derivatives. The reaction was conducted in the presence of chiral, non-racemic quaternary salts derived from the cinchona alkaloids using neutral, non-ionic phosphazene bases.     

Conjugate addition of radicals generated from diacyloxyiodobenzenes to dehydroamino acid derivatives; a synthesis of diaminopimelic acid analogues

Radical decomposition of bis((2S)-N-benzyloxycarbonyl-2-aminopentan-5-carboxy-1-methyl ester)iodobenzene followed by decarboxylation and subsequent conjugate addition with a series of selectively protected dehydroamino acids leads to new analogues of diaminopimelic acid.     

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.     

Effect of substituents on NMR chemical shifts of carboxylic acid esters and nitriles

Conclusions It was shown that the chemical shifts in the NMR spectra of carboxylic acid esters and nitriles can be estimated using the equation for substituted methanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1169–1171, May, 1977.The authors express their gratitude to R. G. Gainullina and T. A. Zyablikova for taking the spectra.     

A copper-catalyzed four-component reaction of arylcyclopropanes,nitriles, carboxylic acids and N-fluorobenzenesulfonimide: facile synthesis of imide derivatives

An unprecedented copper-catalyzed four-component reaction of arylcyclopropanes, nitriles, carboxylic acids and N-fluorobenzenesulfonimide (NFSI) has been successfully developed, which represents the first example of a four-component reaction of non-donor–acceptor cyclopropanes. A wide range of imide derivatives were efficiently synthesized in excellent yields under mild conditions.

An unprecedented copper-catalyzed four-component reaction of arylcyclopropanes, nitriles, carboxylic acids and N-fluorobenzenesulfonimide (NFSI) has been successfully developed, efficiently synthesizing diverse imide derivatives.     

Synthesis of carboxylic acid derivatives of dihydrochalcones

Summary Reaction of chalcones1–8 with thioglycolic acid, 3-mercaptopropionic acid or thiosalicylic acid gives dihydrochalcone derivatives9–23.

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Darstellung von Carbonsäurederivaten von Dihydrochalconen (Kurze Mitt.)

Zusammenfassung Umsetzung der Chalcone1–8 mit Thioglycolsäure, 3-Mercaptopropionsäure oder Thiosalicylsäure liefert die Dihydrochalconeabkömmlinge9 bis23.

     

Catalytic asymmetric Mannich reactions of glycine derivatives with imines. A new approach to optically active alpha,beta-diamino acid derivatives

Imines of glycine alkyl esters react with imines in a diastereo- and highly enantioselective Mannich reaction in the presence of chiral copper(I) complexes as the catalyst to give optically active alpha,beta-diamino acid derivatives. A series of imines of glycine esters derived from glycine and aromatic carbonyl compounds has been screened as substrates for the Mannich reaction with different imines in the presence of various combinations of metal salts and chiral ligands. The benzophenone imine of glycine esters was found to react with N-protected imines in a diastereoselective fashion giving functionalized alpha,beta-diamino acid esters with excellent enantioselectivities. The most effective chiral catalysts are chiral copper(I) complexes having phosphino-oxazoline (P,N)-ligands, and among these ligands, those derived from (1R,2S)-dihydroxy-1,2,3,4-tetrahydronaphthalene gave the best results. The scope of this new catalytic asymmetric reaction of the benzophenone imine glycine esters is demonstrated for the reaction with different N-protected-C-aryl and C-alkyl imines giving the Mannich adducts with excellent optical purity. Furthermore, the synthetic aspects of the reaction are presented by converting the Mannich adducts into alpha,beta-diamino acid derivatives. The relative and absolute configuration of the Mannich adduct have been determined and based on the stereochemical outcome of the reaction a tetrahedral chiral-copper(I)-imino glycine alkyl ester intermediate is proposed. In this intermediate the Re-face of the benzophenone imine glycine ester is shielded by the chiral ligand leaving the Si-face available for approach of the Si-face of the imine. A series of semiempirical calculations has been performed to support the structure of the tetrahedral chiral-copper(I) complex and to account for the influence of the substituents in the chiral phosphino-oxazoline ligands.     

Regioselective halogenation of aminopyrimidinyl-pyrrole carboxylic acid derivatives

The regioselective synthesis of halogenated aminopyrimidinyl-pyrroles as useful scaffolds for the preparation of diversified selective kinase inhibitors is described. The chemistry is simple and mostly based on the use of N-halosuccinimides under mild reaction conditions but the regioselectivity observed is partially unexpected.