Synthesis of α-Halogenated Imidoyl Cyanides1

As part of our investigations in the field of the α-halogenated imine chemistry,¹ we describe herein a convenient and general synthesis of aliphatic α-halogenated imidoyl cyanides 1 (X=Cl,Br). From the synthetic and mechanistic point of view, compounds 1 are expected to exhibit interesting features due to the presence of three functional groups in the molecule.     

On the properties of the anions derived from α-deprotonation of α-(o-carboran-1-yl)- and α-ferrocenyl-1-alkylbenzotriazoles

The synthesis of 1-[(2-R-o-carboran-1-yl)methyl]benzotriazoles (R = Me, Ph) is described. α-Deprotonation of these compounds followed by reactions of the generated carbanions with MeI give the corresponding α-methylated products. Even at room temperature, they exist in solution as an equilibrium mixture of two conformers due to steric crowding around the C^α atom. In contrast, the anions generated by deprotonation of α-ferrocenyl derivatives of 1-methyl- and 1-ethylbenzotriazoles are ambident and are attacked by electrophiles at both the C^α and N(3) atoms.     

Total synthesis of Phytophthora mating hormone α1

Total synthesis of Phytophthora mating hormone α1 (1) has been demonstrated. The required stereochemistries (methyl) are achieved by applying CuI-(S)-Tol-BINAP-catalyzed conjugate addition of Grignard reagents to α,β-unsaturated esters.     

Condensation of 1-Amino-4-azafluorene with α-Diketones and α,β-Unsaturated Ketones

Condensation of 1-amino-4-azafluorene with -diketones and with unsaturated ketones in basic medium gives novel substituted 1,4-diazafluoranthenes and also dihydro-4-azafluoreno[9,9a,1-b,c]cyclohexano[2',3'-e]- and indano[1',2'-e]azepines.     

Stereoselective synthesis of α-aryl-2-benzofuranmethanamines and α-aryl-1H-indole-2-methanamines through palladium-mediated annulation of chiral α-arylpropargylamines

The title compounds, valuable chiral synthons for the synthesis of biologically active compounds, have been prepared in good yield and with high stereoselectivity through palladium-catalyzed heteroannulation of 2-iodophenol or 2-iodo-N-mesylaniline with enantiomerically pure or enriched α-arylpropargylamines.     

1-(1-Alkenyl)benzotriazoles: Novel α-Hydroxyacyl Anion Equivalents for the Synthesis of α-Hydroxy Ketones

α-Lithiated 1-(1-alkenyl)benzotriazoles, generated from the reactions of 1-(1-alkenyl)benzotriazoles with n-BuLi, react with a variety of electrophiles to afford α-substituted 1-(1-alkenyl)benzotriazoles which undergo epoxidation with m-CPBA followed by hydrolysis to give α-hydroxy ketones in good yields. Thus, 1-(1-alkenyl)benzotriazoles behave as α-hydroxyacyl anion equivalents.     

Solvolysis of 1-Chloro-1-Alkenyl Phenyl Sulfides. Synthesis of α-Bromo Phenyl Thiocarboxylic Esters, α-Bromo Alkyl Carboxylic Esters and α-Phenylthio Methyl Carboxylic Esters

1-chloro-1-alkenyl phenyl sulfides treated with bromine followed by hydrolysis or methanolysis give α-bromo phenyl thiocarboxylic esters and α-phenyl-thio methyl carboxylic esters. Direct oxidative solvolysis with bromine and alcohol give α-bromo alkyl carboxylic esters.     

A NOVEL VARIANT OF HUMAN INTERFERON α1 GENE

A 520-base pair human IFN-α gene was isolated by PCR method twice from chromosome DNA of a Chinese (Han Nationality) fetal liver. The nucleotide sequences were determined. These two separately amplified DNA fragments shared the completely identical nucleotide sequence but possessed C and G at positions 410 and 541, respectively, which differ from those oflFN-α1 and IFN-αD previously described. Therefore the deduced amino acid sequence would have an Ala at position 114 and a Val at position 158. At all other sites it has the same amino acids as those in IFN-α1 and IFN-αD. We recommend that IFN-αD gene, IFN-αI gene and IFN-αI/158V gene found in our laboratory, be named IFN-αla gene, IFN-αlb gene and IFN-αlc gene.     

New general synthesis of α-alkoxyketones via α'-alkylation, α-alkylation and α,α'-dialkylation of α-alkoxyketimines

α-Methoxy- and α-ethoxyketones, as important intermediates in organic synthesis and flavor compounds in food chemistry, were synthesized by deprotonation of N-(1-alkoxy-2-propylidene)isopropylamine, prepared by condensation of the corresponding α-alkoxyacetone with isopropylamine, and subsequent reaction of the corresponding 1-azaallylic anions with alkyl halides to afford α'-alkylated, α-alkylated and α,α'-dialkylated ketimines. Hydrolysis of the imino function led to the desired substituted α-alkoxyketones. The ratio of α-, α'-, and α,α'-(di)alkylated compounds depended on the amount of base used and on the nature of the alkylating reagent.     

Asymmetric Synthesis of α, α′-Disubstituted α-Amino Acids Based on Natural (1R)-( + )-Camphor

Optically active nonproteinogenic amino acids[ 1] are valuable compounds of high interest not only owing to their remarkable pharmacological and biological activities, but also for their role as an investigative topographic probe for bioactive conformations of peptides and the mechanisms of enzyme reactions.[2]     

EASY SYNTHESIS OF 1-ALLYL-1-DEOXY-β- AND α- d-LYXOFURANOSES

2,3;5,6-Di-O-isopropylidene-α-d-mannofuranosyl chloride reacted with allylmagnesium bromide with preferential inversion of the anomeric configuration to furnish a mixture of the 1-allyl-1-deoxy-β- and α-d-mannofuranoses. Separation of β and α derivatives was possible only after conversion to the 1-allyl-1-deoxylyxofuranoses 2 and 3. The β configuration of the predominant product 2 was proved using the NOE method.     

The Preparation of α-Phosphonovinylzirconocenes and their Application in the Stereospecific Synthesis of α-Halo-1 -alkenylphosphonates

Hydrozirconation of 1-alkylnylphosphonates gives the organozirconium(Ⅳ) complexes 2 in syn-addition way. Complexs 2 was trapped with NCS, NBS or I2 to afford stereodifined α-halo-1-alkenylphosphonates in moderate to high yields.     

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]     

Efficient synthesis of N-Me, N-Boc-protected α-hydrazinoacids: access to 1:1:1 [N-Me α-hydrazino/α/N-Me α-hydrazino]trimers

The preparation of optically pure N^α-Me, N^β-Boc-protected α-hydrazinoacids in large scale is described via a S_N2 protocol. These compounds were used as starting materials for the synthesis of 1:1:1 [N^α-Me α-hydrazino/α/N^α-Me α-hydrazino]trimers.     

Pharmacophore development for antagonists at α1 adrenergic receptor subtypes

Summary Many receptors, including ₁ adrenergic receptors, have a range of subtypes. This offers possibilities for the development of highly selective antagonists with potentially fewer detrimental effects. Antagonists developed for _1A receptors, for example, would have potential in the treatment of benign prostatic hyperplasia. As part of the molecular design process, structural features necessary for the selective affinity for _1A and _1B adrenergic receptors have been investigated. The molecular modelling software (particularly the Apex module) of Molecular Simulations, Inc. was used to develop pharmacophore models for these two subtypes. Low-energy conformations of a set of known antagonists were used as input, together with a classification of the receptor affinity data. The biophores proposed by the program were evaluated and pharmacophores were proposed. The pharmacophore models were validated by testing the fit of known antagonists, not included in the training set. The critical structural feature for selectivity between the _1A and _1B adrenergic receptor sites is the distance between the basic nitrogen atom and the centre of an aromatic ring system. This will be exploited in the design and synthesis of structurally new selective antagonists for these sites.