Synthesis and Crystal Structure of (Z)-Ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate

The compound (Z)-ethyl 5-(phenylamino)-3-(phenylimino)-3H-1,2-dithiole-4-carboxylate 3 has been synthesized by the reaction of ethylacetoacetate 1 and phenylisothiocyanate 2. Its structure has been established by ¹H NMR, ¹³C NMR, infrared, mass spectra, and x-ray crystallography.      

A Rapid and Efficient Method for Dehydration of Primary Amides to Nitriles. Preparation of Acrylonitrile Derivatives

Chloromethylene iminium salts (Vilsmeier reagents) have a long history and thoroughly investigated chemistry⁽¹⁾. Chloro-N, N-dimethylforminium chloride 1 is most conveniently generated by the reaction of N, N-dimethylformamide (DMF) with oxalyl chloride⁽²⁾. The reagent has also been obtained usingthicnyl chloride at elevated temperature and a variety of acid chlorides^(1b). The literature describes several examples of the use of thionyl chloride in combination with DMF in which 1 or a related species is thought to function as the reactive intermediate in the transformation of amides to nitriles⁽³⁾.     

Novel Chiral Bisformamide-Promoted Asymmetric Allylation of Benzaldehyde with Allyltrichlorosilane

Novel chiral bisformamides have been prepared from (R,R)-1,2-cyclohexanediamine and utilized as Lewis bases in the asymmetric allylation of benzaldehyde with allyltrichlorosilane. The reaction in the presence of Lewis base 1i gave an 83:17 enantiomeric ratio (R/S) of the products in 90% isolated yield.      

Some Novel Thiopyrimidine Nucleoside Analogs: Synthesis and In Vitro Antimicrobial Evaluation

Some new S-alkyl derivatives of indeno[1′,2′:4,5]thieno[2,3-d]pyrimidine 2–8 were prepared starting with pyrimidine-2(1H)-thione derivative (1). Also, treatment of compound 1 with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide or 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose afforded nucleosides 9 and 12, respectively. Furthermore, deprotection of the latter blocked nucleosides was achieved in methanolic ammonia to afford the desired free S-nucleoside derivatives 10 and 13, respectively. Some prepared products were screened for antimicrobial activity, and some of them showed promising activity.     

A New Approach to the Efficient Method for the Asymmetric Synthesis of (S)-O-, M-, P-Fluorophenylalanines and Their 2-Methyl-substituted Analogs

Abstract

The reactions of asymmetric C-alkylation of glycine and alanine in Ni^II complexes of their Schiff's bases with modified chiral auxiliaries (S)-2-N-[(N′-2-chlorobenzylprolyl)amino]benzophenone and (S)-2-N-[N′-(3,4-dimethylbenzylprolyl)amino]benzophenone by fluorine-substituted benzyl halogenides have been studied. As a result, a highly stereoselective and relatively rapid method for the asymmetric synthesis of (S)-o-, m-, p-fluorophenylalanines and their 2-methyl substituted analogs has been developed.     

Synthesis of the Precursor of K252a and Its Analogs

A practical and efficient asymmetric synthesis of the key precursor furanose 3 for the synthesis of K252a and CEP-701 has been achieved in nine steps with an overall yield of 12.8% from (R)-methyl β-hydroxytetradecanoate 5, an industrial intermediate for production of orlistat.      

Regioselective Intramolecular Carbon-Hydrogen Insertion in Copper-Catalyzed Carbenoid Decompositions of cis-1-Methyl-3-Arylcyclohexane-1-Diazomethyl Ketones : Some Synthetic Applications

Recently, we have developed¹ a new route for the stereo-specific introduction of an angular carboxyl or functionalized methyl groups² in a rigid hydrophenanthrene moiety. The key step in this approach is a regioselective intramolecular α-keto carbenoid insertion across the benzylic C-H bond (at C-4a) in CuSO₄-catalyzed thermal decomposition of the diazoketones and to the corresponding tetracyclic ketones and in moderate to good yields. A modified procedure³ of carbenoid decomposition of these diazoketones, in the presence of Cu₂O under irradiation with tungsten filament lamp, improves the yields of the desired C-H insertion products. Thus, the ketones and have been prepared now in consistently higher yields (53-55%) from the pure diazoketones , m.p. 125-127°, and , m.p.     

The Nitro Ketal Approach to Furane Systems. Total Synthesis of Racehic Bilobanone

Continuing our studies with the chemistry of ketals of β-nitro ketones¹, we wish to describe a new furane synthesis exemplified by a total synthesis of the sesquiterpene bilobanone 1 ².