Synthesis of New Benzoimidazole Derivatives

The reactions of cryptotanshinone and tanshinone llA with cadaverine and putrescine were investigated. Six new compounds, four with imidazole functional groups and two with oxazole groups, were obtained. The possible reaction mechanism was proposed.     

Synthesis of New Fluorinated Podophyllotoxin Derivatives

Five fluorinated podophyUotoxin derivatives were synthesized using dimethylamino-sulfurtrifluoride (DAST).     

Synthesis,In Vitro α-Amylase Activity,and Molecular Docking Study of New Benzimidazole Derivatives

Russian Journal of Organic Chemistry - New benzimidazole derivatives were synthesized by reacting substituted phenacyl bromides with 1H-benzimidazole-2-thiols. The synthesized compounds were...     

Synthesis of New α-Heterocyclic α-Aminophosphonates

α-heterocyclic α-aminophosphonates were obtained in good yields by N-of several nitrogen heterocycles with α-azido-α-aminophosphonate 1. ¹ Elachqar, A., El Hallaoui, A., Roumestant, M. L. and Viallefont, Ph. 1994. Synthetic Comm, 24: 1279 [CSA][Taylor & Francis Online], [Web of Science ®] , [Google Scholar]     

The Reaction of N-Phenyliminoketenylidenetriphenyl-phosphorane with α,β-Unsaturated Carbonyl Compounds. Synthesis of New Pyran Derivatives

Abstract

The reaction of N-phenyliminoketenylidenetriphenylphosphorane [a] (1), with 2-benzylidene-1, 3-indandione (2), 1,2-diphenyl-3,4-pyrazolidenedione (3)and/or 5-benzylidene barbituric acid (4) has been investigated. When ylide 1 was allowed to react with compounds 2, 3 or 4 in THF at ambient temp. the corresponding new pyrano-phosphoranylidenes 5, 6 or 7 were obtained. The elemental microanalyses, IR, ¹H NMR, ³¹P NMR and MS data agree with the structure of the cyclic iminophosphoranes by [4+2]-cycloaddition and exclude 4-membered ring structure by [2+2]-cycloaddition. When the Wittig reaction was carried on the pyrano-phosphoranes 5, 6 or 7 using p-nitrobenzaldehyde, the exocyclic olefins together with triphenylphosphine oxide were isolated.     

Synthesis of New Purine Derivatives Containing α- and ω-Amino Acid Fragments

Russian Journal of Organic Chemistry - New conjugates of purine and 2-aminopurine with several α- and ω-amino acids have been synthesized following two approaches based on the...     

Synthesis and Characterization of α-Bromo Chalcone Derivatives

α-Bromo chalcones containing 2-thiene ring were prepared in good yields by the condensation of 1-(thien-3-yl)ethanone with aromatic aldehydes, followed by bromination with bromine and selective dehydrobromination with triethyl amine at room temperature.     

Synthesis and Antitumor Activity of New Derivatives of Podophyllotoxin

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A New and Efficient Synthesis of Wedelolactone Derivatives

A new and facile method based on an intermolecular cycloaddition was described for the synthesis of wedelolactone derivatives.     

Soluble Polymer-Supported Synthesis of α-Amino Acid Derivatives

Due to the central role played by α-amino acid in chemistry and biology, the development of versatile and new methodology for the synthesis of natural and unnatural α-amino acid has emerged as an important and challenging synthetic endeavour for organic chemists.[1] Among the various methodologies reported for α-amino acid synthesis, [2,3] the solid-phase organic synthesis (SPOS) has served as an important approach. [4] However, inherent prob lems on solid supports are reactive site accessibility, site-site interaction and monitoring of the reaction.     

Synthesis of α-N-Ethylamino Acids and their Derivatives

 A new synthesis of α-N-ethylamino acids starting from α-amino acids using hexafluoroacetone as protecting and activating agent is described. The hexafluoroacetone-protected N-ethylamino acid derivatives obtained are activated lactons. Therefore, they can be directly transformed without the need of an additional activation step with various nucleophiles into the corresponding carboxylic acid derivatives.     

A New Synthesis of α-Methylene Carbinols

The synthetic utility of α-methylene carbinols has prompted considerable recent preparative interest. However, many of the reported methods¹ lack scope and require reagents or reaction conditions which are incompatible with sensitive functional groups. We report below two closely related methods for the synthesis of α-methylene carbinols which are based on the reductive elimination of β,γ-epoxysulfones. Both methods give the desired products in moderate overall yield in a four-step sequence which is mild and experimentally facile.     

New Methodology for the Synthesis of α,α-difluoroketones

A new methodology is described for the synthesis of α,α-difluorinated ketones by the addition of organolithium reagents to α,α-difluoro-N-methoxy-N-methyl amides (Weinreb amides).     

Synthesis of New Thiazine and Thiosemicarbazone Derivatives from D-Xylose

Thioureas have strong antifungal activities1 and their antimicrobial and insecticidal properties have been documented for more than fifty years2. Recently thiourea derivatives have been reported to possess antitubercular, antithyroid and anticancer3 prope…     

New Synthesis of α-Bromo-α,β-Unsaturated Esters

A synthesis of α-bromo-α,β-unsaturated esters 2 from tert-butyl α-(trimethylsilyl)-α-bromoacetate (1) and carbonyl compounds is described.     

A New Synthesis of α-Aryltelluro Esters

Aryltellurenyl iodides react with Reformatsky reagents in dry THF at room temperature rapidly to produce α-aryltelluro esters in good yields.     

Organocatalytic Multicomponent Synthesis of α/β-Dipeptide Derivatives

A straightforward multicomponent Knoevenagel-aza-Michael-cyclocondensation reaction involving readily available hydroxamic acid-derived from naturally occurring α-amino acids allows a diversity-oriented synthesis of novel isoxazolidin-5-ones possessing an N-protected α-amino acid pendant with good to high diastereoselectivities thanks to a match effect with a chiral organocatalyst. These diversely substituted heterocycles, easily isolated as a single diastereoisomer, proved to be versatile platforms for the formation of an array of α/β-dipeptide fragments.     

Syntheses of New Carbonyl Derivatives from α-Halohetaryl Ketones

The Kröhnke reaction of 2-bromoacetylphenoxathiin and 2--bromophenoxathiin 10,10-dioxide, through N-ylide and S-ylide intermediates, leading to the corresponding glyoxals, was described. The condensation reaction of 2--bromoacetylphenoxathiin with aromatic o-hydroxy aldehydes and further cyclization to new furan derivatives was also performed. The new compounds were characterized through elemental analysis and spectral data (IR, ¹H NMR and ¹³C NMR).     

New Method for the Synthesis of α-Amino Substituted Benzyl Phosphonic Acids and their Derivatives

Abstract

A new method for the synthesis of α-amino-substituted benzyl-phosphonic or phosphinic acid (5) was descrided. By reaction of phosphoramides (1) with substituted benzaldehydes (2) and phosphite (3) in the presence of BF₃, α-(N-phosphorylamino)-substituted benzylphosphonates or phosphinates (4) was obtained in moderate to good yield. This method distinguished itself by the simple manipulation and higher purity of the product resulted in both steps of the reaction sequences. Meanwhile, aminophosphonic esters are useful intermediated in the phosphorus peptide synthesis. The influence of variation in structure of 1, 2 and 3 on the yield of 5 was evaluated on the basis of sturcture-reactivity studies.