Novel α-methyl(benzyl)deoxyvasicinones

A method was developed to prepare -methyl(benzyl)deoxyvasicinones by alkylation of -hydroxy- methylidenedeoxyvasicinone. It has been shown that the reaction proceeds anomalously through a deformylation step.Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 407–409, September–October, 2004.     

Total synthesis of (±)-clavam-2-carboxylic acid

Racemic clavam-2-carboxylic acid has been obtained by a six-stepsynthesis from readily available starting materials.     

Reaction of arylidene-2-naphthylamines with the ethyl ester of (2-quinolyl)-β-oxopropionic acid

The reaction of arylidene-2-naphthylamines with the ethyl ester of (2-quinolyl)--oxopropionic acid results in the synthesis of ethyl esters of 1-(2-quinolyl)-3-arylbenzo[f]quinoline-2-carboxylic acids. All the theoretically possible intermediate reaction products were isolated: the amino esters of 2-quinoline--oxopropionic acid, the hydroxy esters of tetrahydro- and esters of dihydrobenzo[f]quinoline-2-carboxylic acid, as well as the by-products — the ethyl ester of 2-quinolyl--(R-benzylidene)--oxopropionic acid. The IR, UV, and mass spectra of the synthesized compounds are discussed.Institute of Physical Organic Chemistry, Belorussian Academy of Sciences, Minsk 220603. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1406–1410, October, 1994. Original article submitted October 5, 1994.     

Design and synthesis of trans-3-aminopyran-2-carboxylic acid (APyC) and α/β-peptides with 9/11-helix

A new β-amino acid, trans-3-aminopyran-2-carboxylic acid (APyC), was designed and synthesized from (R)-glyceraldehyde derivative and used in the synthesis of α/β-peptides in a 1 : 1 alternating pattern with d-Ala. The presence of oxygen atom at the Cβ(2)-position in APyC was envisaged to provide opportunity for additional interaction. These hybrid peptides have shown the presence of 9/11-helix through extensive NMR and MD studies. The amide protons of d-Ala, in addition to participating in 9-mr H-bonding with CO of succeeding β-residue, were also involved in additional electrostatic interaction with pyran ring oxygen of preceding β-residue, which facilitated further stabilization to the 9/11-mixed helix. The study thus results in a new 'motif' for a 9/11-helix, and the first example from a cyclic β-amino acid.     

Synthesis of (E)- and (Z)-α,β-difluorourocanic acid

Horner-Emmons fluoroolefination of an aryl aldehyde followed by introduction of a second fluorine via “FBr” addition provides an original approach to the preparation of 1-alkyl-2-aryl-1,2-difluoroethenes. The utility of this procedure is demonstrated by the preparation of (E and Z)-α,β-difluorourocanic acid.     

Synthesis and Bioactivity of Some New 2-(Alkoxy carbonyl alkyl)-6-bromo-3,4-dihydro-3-(α-methyl benzyl)-2-oxo- benzo[e] [2H-1,3,2-oxazaphosphinine] Derivatives

Synthesis of some new 2-(alkoxy carbonyl alkyl)-6-bromo-3,4-dihydro-3-(α-methyl benzyl)-2-oxo-3-benzo- [e][2H-1,3,2-oxazaphosphinine] derivatives was accomplished through a two step process, which involves the condensation of 2-[(α-methylbenzyl amino)methyl]-4-bromophenol (1) with phosphorus oxychloride in equimolar quantities in the presence of triethylamine in dry toluene in 50—55 ℃ producing the corresponding intermediate (2), and subsequent reaction with the amino acid alkyl ester in dry tetrahydrofuran in the presence of triethylamine at different temperatures. They exhibited significant antibacterial and fungal activity.     

Dehydrochlorination of trichloro(α,β-dichlorophenethyl)-silane and of trichloro[α-chloro-α-(chloromethyl)benzyl]silane

Summary The general character of the rearrangement undergone by ,-dichloroalkyltrichlorosilanes in the course of their dehydrochlorination by means of aluminum chloride was confirmed by reference to a new example of the reaction.     

Synthesis of benzyl O-(2,3,3'-tri-O-acetyl-β-D-apiofuranosyl)-(1→3)-2,4-di-O-benzoyl-α-D-xylopyranoside and its X-ray structure

The protected apiose-containing disaccharide, benzyl O-(2,3, 3'-tri-O-acetyl-β-D-apiofuranosyl)-( 1→3)-2, 4-di-O-benzoyl-α-D-xylopyranoside, was synthesized and its X-ray structure provided.     

Synthesis of N-(methoxycarbonyl or isopropylcarbamoyl- methoxyphosphonyl)-α-amino acid ester and their stereomers

N-(methoxycarbonyl-methoxyphosphonyl)-α-amino add esters (I) were synthesized via the reaction of the corresponding phosphonyl chloride with amino acid ester hydrochlorides in the presence of a base. Compound I was aminated to yield N-(isopropylcarbainoyl-methoxyphosphonyl)-α-amino acid esters (II). With l-amino acids as starting materials, the isomers of products I and II were separated and their configurations were confirmed by the single crystal X-ray diffraction of II.     

Efficient synthesis and resolution of (±)-1-[2-carboxy-6-(trifluoromethyl)phenyl]pyrrole-2-carboxylic acid

A novel, efficient synthesis and resolution of (±)-1-[2-carboxy-6-(trifluoromethyl)-phenyl]pyrrole-2-carboxylic acid has been developed for the preparation of new members of optically active atropisomers. The e.e. values were determined by a highly sensitive ¹⁹F NMR spectroscopic method using β-cyclodextrin as chiral complexing agent. Single-crystal X-ray structures of the two diastereoisomeric salts and consequently, the absolute configurations of the enantiomers are also reported.     

α-hydroaxyalkyl(benzyl)furozans and α-hydroxyalkyl(benzyl)furoxans synthesis and reactivity

A general and simple preparative method for the synthesis of -hydroxyalky(benzyl)furazan and -furoxan derivatives is proposed, The method involves reduction of acyl or ethoxycarbonyl substituents in these heterocyclic compounds with NaBH₄ in ethanol. Based on the alcohols thus prepared, a number of previously unknown functional derivatives (-nitroxyalkyl--haloalkyl-, and -azidoalkylfurazans and -furoxans) have been synthesized.Translated fromInvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7. pp, 1782–1788, July, 1996.     

Reaction of benzylidene-2-naphthylamine with the ethyl ester of 3-pyridyl-β-oxopropionic acid

The reaction of benzylidene-2-naphthylamine with ethyl -(3-ethyl)--oxopropionate under various conditions gave the ethyl ester of -(2-naphthylamino)benzyl--(3-pyridyl)--oxopropionic acid, 1-(3-pyridyl)-3 phenylbenzo[f]quinoline, ethyl ester of 1-(3-pyridyl)-3-phenylbenzo[f]quinoline-2-carboxylic acid, and N-(2-naphthyl)amide of -(3-pyridyl)--oxopropionic acid. The IR, UV, and mass spectra of the products were studied and the pathways for their formation were discussed.Institute of Physical Organic Chemistry, Belorussian Academy of Sciences, Minsk 220603. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 807–810, June, 1996. Original article submitted December 30, 1995.     

Enantiodivergent synthesis of cyclobutyl-(Z)-α,β-dehydro-α-amino acid derivatives from (−)-cis-pinononic acid

The two enantiomers of the title dehydroamino acids (DHAAs) have been synthesized through respective Wadsworth–Emmons condensations of a suitable phosphonate with enantiomeric cyclobutyl aldehydes. These compounds, in turn, were prepared by selective manipulation of the functional groups starting from (−)-cis-pinononic acid as the common chiral precursor. The CD spectra of the prepared DHAAs are described. These products are suitable for the stereocontrolled synthesis of diferent types of saturated cyclobutyl amino acids and their derivatives.     

N- vs O-Coordination in cyclomanganation of 1,5-diaryl-3-(2-pyridyl)pentane-1,5-diones and 3-(2-pyridyl)chalcones; cyclomanganation at saturated carbon and the crystal structure of [1,5-diphenyl-κC-3-(2-pyridyl- κN)pentan-2-yl-κC-1,5-dione-κOκO]tetracarbonylmanganesetricarbonylmanganese

Reaction of 1,5-diphenyl-3-(2-pyridyl)pentane-1,5-dione (5a) with 2.5 moles of benzylpentacarbonylmanganese in petroleum spirit under reflux gives a small amount of the symmetric di-aryl-manganated product [1,5-diphenyl-κC²-3-(2-pyridyl)pentane-1,5-dione-κO¹κO⁵]bis-(tetracarbonylmanganese) (7a), but mostly [1,5-diphenyl-κC²-3-(2-pyridyl-κN)pentan-2-yl- κC²-1,5-dione-κO¹κO⁵]tetracarbonylmanganesetricarbonylmanganese (6a) which is manganated at only one aryl carbon [by Mn(CO)₄] but also [by Mn(CO)₃ with N and O coordination] at the methylene carbon adjacent to the Mn(CO)₄-coordinated ketone carbonyl. The latter is a rare example of direct cyclomanganation at a saturated carbon and the only known case adjacent to a carbonyl group; the X-ray crystal structure of 6a is reported. With 3 moles of benzylpentacarbonylmanganese the yield of 6a remains unchanged but some trimanganation product [1,5-diphenyl-κC^2′κC^2?-3-(2-pyridyl-κN)pentan-2-yl-κC²-1,5-dione-κO¹κO⁵]tris-(tetracarbonylmanganese) (8a) is formed, presumably from 7a. Routes to products are proposed and activating factors considered. 1,5-Di-(2-thienyl)-3-(2-pyridyl)pentane-1,5-dione (5b) and its 3-thienyl isomer (5c) similarly give 6a analogues [1,5-di-(2-thienyl-κC³)-3-(2-pyridyl-κN)pentan-2-yl-κC²-1,5-dione-κO¹κO⁵]tetracarbonylmanganesetricarbonylmanganese (6b) and [1,5-di-(3-thienyl-κC²)-3-(2-pyridyl-κN)pentan-2-yl-κC²-1,5-dione-κO¹κO⁵]tetracarbonylmanganesetricarbonylmanganese (6c).Also reported are the mono-cyclomanganation product [1-(2,6-dimethoxyphenyl)-3-(2-pyridyl-κN)prop-2-en-2-yl-κC²-1-one]tetracarbonylmanganese (16) and dicyclomanganation product [1-(2,5-dimethyl-3-thienyl-κC⁴)-3-(2-pyridyl-κN)prop-2-en-2-yl- κC²-1-one-κO ]bis-(tetracarbonylmanganese) (17) from reaction of the respective (E)-1-aryl-3-(2-pyridyl)prop-2-en-1-ones (3-(2-pyridyl)chalcones), the first reported examples of enone metallation at the α-carbon via N-coordination by a β-2-pyridyl group.     

Synthesis of propyl O-(α-L-rhamnopyranosyl)-(1→3)-[2,4-di-O-(2s-methylbutyryl)-α-L-rhamno-pyranosyl]-(1→2)-(3-O-acetyl-β-D-glucopyranosyl)-(1→2)-β-D-fucopyranoside,the tetrasaccharide moiety of Tricolorin A

Propyl O-(α-L-rhamncpyranosyl)-(1→3)-[2,4-di-O-(2s-methylbutyryl)-α-L-rham-nopyranosyl]-(1→2)-(3-O-acetyl-β-D-glucopyranosyl)-(1→2)-β-D-fucopyranoside (1), the tetrasac-charide moiety of Tricolorin A, was synthesized in total 23 steps with a longest linear sequence of 10 steps, and overall yield of 3.7% from D-Glucose. The isomerization of the dioxolane-type berzyli-dene in the presence of NIS/AgOTf was observed. Tetrasaccharide 1 exhibited no activity against the cultured P388 cell as Tricolorin A did.