Reactions of acetals with alkyl 2-bromovinyl ethers

Summary A study was made of the condensation of benzaldehyde and acetaldehyde acetals with alkyl 2-bromovinyl ethers, as a result of which bromo ethoxy acetals of general formula RCH(OC₂H₅)CHBrCH(OR)₂ (R=C₆H₅ and CH₃) were formed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 282–285, February, 1965     

Wittig rearrangement of allyl furfuryl and allyl thienyl ethers and sulfides and their benzo-derivatives

Treatment of allyl furfuryl ethers and sulfides with butyllithium results in metallation at the free -position of the heterocycle, with partial Wittig rearrangement to the isomeric alcohols and sulfides and ring opening. With the benzo-derivatives, Wittig rearrangement and ring opening takes place.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 883–888, July, 1987.     

Reactions of furfuryl alcohols with maleic anhydride

The reactions of some furfuryl alcohols with maleic anhydride have been reinvestigated and, for the first time, conditions defined for the production of intramolecular Diels-Alder adducts. In basic conditions these adducts yield phthalides in high yields.     

Chemo- and regioselective reaction of vinyl furfuryl ethers with alcohols

Furfuryl and tetrahydrofurfuryl vinyl ethers reacted with various alcohols under mild conditions (20?C25°C, 1?C3 h, 1 wt % of CF₃COOH) with high chemo- and regioselectivity to give the corresponding Markovnikov adducts at the vinyl group in up to 93% yield.     

Synthesis and conformational analysis of furfuryl vinyl ethers

Five furfuryl vinyl ethers were synthesized from the corresponding furfuryl alcohols and acetylene at high and atmospheric pressures in superbasic medium KOH-DMSO. On the example of 2-vinyloxymethylfuran and 2-vinyloxymethyltetrahydrofuran, their conformational structures have been studied by quantum chemistry methods, NMR and IR spectroscopy. In particular, from the results of the quantum-chemical calculations, as well as on the basis of experimental measurement and nonempirical calculations of the high level spin-spin coupling constants ¹³C-¹³C and ¹³C-¹H, a conclusion has been drawn on the s-cis-orientation of the vinyl groups with respect to the C_α-O bond in the predominant conformers of 2-vinyloxymethylfuran and 2-vinyloxymethyltetrahydrofuran.     

Transalkylation of alkyl aryl sulfides with alkylating agents

The reaction of methyl iodide with tert-butylphenylsulfide in DMF leads to a transalkylation that produces methylphenylsulfide. This transalkylation reaction was further studied by ¹H NMR spectroscopy. The polarity of the solvent, the electron density on the sulfur atom, and the strength of the alkylating agent (MeI, EtI, BuI, dimethyl sulfate, or dimethyl carbonate) played important roles in the reaction. The suggested mechanism of the reaction involves the formation of a dialkyl aryl sulfonium salt that subsequently eliminates the radical. This mechanism was supported by the observation of higher conversion rates for compounds with more branched alkyl groups on the sulfur atom, which may lead to the formation of more stable radicals.     

Reactions of 3,5-diethoxycarbonyl 1,2,4-diazaphospholes and arsoles with alkyl vinyl ethers,sulfur ylides,and diazocompounds

3,5-Diethoxycarbonyl 1,2,4-diazaphospholes and arsoles undergo N-alkylation by reaction with alkyl vinyl ether, sulfur ylides, and diazocompounds, owing to the acidity of the NH group. © 1995 John Wiley & Sons, Inc.     

Reactions of sulfur dichloride with allylthienyl sulfides

The reaction. of allyl-2-thienyl sulfide with sulfur dichloride yields products of intermolecular- addition of intermediately formed sulfenyl chloride to the starting sulfide, and in the case of allyl-3-thienyl sulfide, intramolecular cyclization also takes place with formation of a compound of the thienodithiin series.Moscow State University, Chemistry Faculty, Moscow 119899. A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, Moscow 117813. Translated Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 767–769, June, 1994. Original article submitted April 18, 1994.     

Oxidative transformations of alkyl caryophyllanyl sulfides

Sesquiterpene sulfoxides and sulfones were synthesized in up to 56 and 74% yields, respectively. The oxidation of sulfides was accompanied by rearrangement of the epoxide fragment to allylic alcohol with subsequent oxidation. The isomerization of 4,5-epoxycaryophyllane-15-thiol afforded for the first time 4,11,11-trimethyl-8-(sulfanylmethyl)bicyclo[7.2.0]undec-3-en-5-ol in 40–45% yield.     

Reactions of piroxicam with alkyl iodides

Alkylation of piroxicam with a homologous series of alkyl iodides gave reversibly formed O-alkyl products 1 as well as unexpected, irreversibly formed zwitterionic compounds 2 , alkylated on the pyridine nitrogen, and O,N-bis-alkyl products 3 . Proof of structure was accomplished by nmr and X-ray crystal analysis. Product distribution ratios were determined by hplc and are explained by the Hard-Soft Acid-Base principle.