A novel synthesis of benzofuran and related compounds. III. The vilsmeier reaction of phenoxyacetaldehyde diethyl acetals

A novel synthesis of 2-benzofurancarbaldehydes by the Vilsmeier reaction of phenoxyacetaldehyde diethyl acetals is described.     

Formation of benzofuran and 2H-chromene structures in one reaction. A novel synthesis of 2H-chromene derivatives

Heating the morpholinal of nitrosalicylic aldehyde with methyl propiolate in acetonitrile in the presence of Cul affords an equimolar mixture of 2-methoxycarbonylmethyl-3-morpholino-5-nitrobenzofuran and 3-methoxycarbonyl-2-morpholino-6-nitro-2H-chromene, the structures of which were determined by X-ray analysis. Only the 2H-chromene mentioned above was obtained in the absence of Cul and solvent.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1222–1228, May, 1996.     

Organosilicon compounds I. A novel synthesis of organosilicon substituted furfurals

The use of the diethylacetal moiety of 2-furfuraldiethylacetal as a carbonyl blocking agent during n-butyllithium metalations is described. The synthesis of 5-silicon substituted furfurals is accomplished for the first time with NMR data being employed as a means of structure proof. Furthermore, the isolation of the uniquely stable organo-lithium salt, 5-lithio-2-furfuraldiethylacetal, is reported.     

Syntheses of salvilenone and related compounds: I. A total synthesis of salvilenone

The first total synthesis of a novel phenalenone diterpene salvilenone (1) isolated from a traditional Chinese medicine, Dan-Shen (Salvia miltiorrhiza. L.), has been achieved in thirteen steps started from resorcinol dimethyl ether (5).     

Research on heterocyclic compounds. XLII. The vilsmeier reaction in the synthesis of imidazo[1,2‐a]pyrimidine derivatives

The Vilsmeier reaction on imidazo[1,2‐a]pyrimidine ring is reported. The 3‐formyl derivative obtained is oxidized to yield the corresponding carboxylic acid.     

The synthesis of thiaolivacine and related compounds

1,5-Dimethylbenzothieno[2,3-g]isoquinoline (thiaolivacine) has been prepared from the nitro-vinyl derivative of 4-methyl-3-dibenzothiophenecarboxaldehyde. Using the same aldehyde, 4-des-methylisothiaolivacine was prepared by formation of the Schiff's base with aminoacetaldehyde diethyl acetal followed by cyclization. Similar methods yielded the pyrido-N-isomer, 1-des-methylthiaolivacine, from 4-methyl-2-dibenzothiophenecarboxaldehyde. The thiaolivacine parent unsubstituted ring system, benzothieno[2,3-g]isoquinoline, was prepared from 2-dibenzothio-pheneearboxaldehyde by the aminoacetaldehyde approach, as was the corresponding oxygen analog, benzofuro[2,3-g]isoquinoline, from 2-dibenzofurancarboxaldehyde. The 100 MHz spectra of these fused isoquinolines are recorded and correlated.     

Studies on quinoline derivatives and related compounds. VI. A novel displacement reaction of 1-ethylquinolinium iodides with nucleophiles

The reaction of 4-amino- ( 3a ) and 4-anilino-3-carbethoxy-1-ethyl-6,7-methylenedioxy-quinolinium iodide ( 3b ) with nucleophilic reagents produced 7-substituted 4-amino-3-carboxy-1-ethyl-6-hydroxyquinolinium betaines ( 5b-d ) and 7-substituted 1-ethyl-1,4-dihydro-6-hydroxy-4-phenylimino-3-quinolinecarboxylic acid ( 6b-d ), respectively, which led to 7-substituted 1-ethyl-1,4-dihydro-6-hydroxy-4-oxo-3-quinolinecarboxylic acids ( 1b-d ) by alkaline hydrolysis. With a variety of 1-ethyl-1,4-dihydroquinoline carboxylates ( 16a-e ) these novel displacement reactions were attempted.     

A straightforward synthesis of indole and benzofuran derivatives

A new methodology for the synthesis of indole and benzofuran derivatives has been devised. The starting materials, ortho-substituted aryl diynes, have been easily converted into new unsaturated bis-indolyl and bis-benzofuran derivatives and into 2-ethynylindole and 2-ethynylbenzofuran. Both these products have been further elaborated into more complex unsaturated indole-benzofuran and bis-benzofuran derivatives.     

Silver(I) fluoride and related compounds in chemical synthesis

Silver(I) fluoride is a versatile tool in desulfuration‐fluorination reactions with thiuram disulfides and thioureas. Reactions of AgF and trimethyl(perfluoroorgano)‐ and trimethyl(alkynyl)‐silanes offer a convenient approach to the corresponding organosilver derivatives, which are excellent reagents for oxidative organylations of group 12–16 elements. Reactions of AgF and elements of groups 13–16 open a convenient access to the corresponding fluorides. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:561–566, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10102     

Fluorohalogeno compounds. I. The grignard reaction of some fluorohalogenoethanes

An extension of the scope of the Grignard reaction of fluorinated compounds is reported. Fluorohalogenoethanes of the general formula CF₃CXYZ ( X = F,Cl,Br ; Y,Z = Cl,Br ) were found to undergo smoothly the metal-halogen exchange reaction with alkyl- or aryl-magnesium halides at low temperature to yield organometallic compounds CF₃CXYMgHal. The Grignard compounds were reacted with a series of aldehydes and ketones to give the corresponding alcohols in good to moderate preparative yields.     

Ei reaction of sulphilimines and related compounds

Ei reaction of tertiary amine oxides, i.e. the Cope elimination and that of sulphoxides, are briefly reviewed. N-p-Tosylsulphilimines also undergo facile Ei reaction upon heating and the stereospecificity of the reaction is better than that of the corresponding sulphoxides and even somewhat better than that of the tertiary amine oxides.A general outlook on research on the Ei reactions of sulphilimines and the mechanism of the reaction are discussed in comparison with those of similar Ei reactions which proceed via 5-membered cyclic transition states.     

A novel synthesis of half-protected 1,3-dicarbonyl compounds

It has been found that the reaction of enol silyl ethers with 2-ethoxy-1,3-dithiolane proceeds smoothly in the presence of zinc chloride catalyst to afford half-protected 1,3-dicarbony1 compounds in moderately good yields.     

A novel synthesis of cis-dihydro-rose oxide and related stereochemistry

A new synthesis of cis-dihydro-rose oxide from elsholtzia oil is presented. The stereochemistry of catalytic hydrogenation of elsholtziol is discussed, and configurations of the diastereoisomers of the resulting tetrahydroelsholtziol have been deduced with the aid of gas chromatography, infrared spectroscopic analysis and conformational analysis. Stereochemical study of catalytic dehydration of tetrahydroelsholtziols indicates that the dehydration-rearrangement reactions follow a (trans-elimination process.     

Reaction of N-cyanoformimidates with some heterocyclic compounds. A new synthesis of 5-azaadenine and related compounds

3-Amino-1,2,4-triazoles and 2-aminobenzimidazole were reacted with N-cyanoimidates to give 5-amino-1,2,4-triazolo[2,3-a]-1,3,5-triazines (5-azaadenines) and 4-aminobenzimidazo[1,2-a]-1,3,5-triazines, respectively. The structures of the compounds obtained were confirmed through the comparison with some of the possible isomers prepared by independant methods.