29848-43-9Relevant academic research and scientific papers
Substituted pyridines/pyrimidines, their preparation, and their use as pesticides
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, (2008/06/13)
The present invention relates to novel substituted pyridines/pyrimidines of the formula I where A is CH or N; X is NH, oxygen or S(O)qwhere q is 0, 1 or 2; Y is a direct bond or CH2; Z is oxygen, NR7or S(O)mis 0
Intramolecular rearrangement of epoxides generated in situ over titanium silicate molecular sieves
Bhaumik, Asim,Tatsumi, Takashi
, p. 349 - 356 (2007/10/03)
Open chain unsaturated alcohols 1, having the general formula R1R2C=CH(CH2)CR1R2OH (where R1, R2 = H or CH3, and n = 1-3) and carbocyclic unsaturated alcohols of similar type have been efficiently cyclized to the corresponding hydroxytetrahydrofuran or hydroxytetrahydropyran over titanium silicate molecular sieves (TS-1 and Ti-beta), in one pot under mild liquid phase reaction conditions using dilute hydrogen peroxide as oxidant. When the hydroxy nucleophile may attack either of the activated carbon atoms of the epoxides generated in situ, to lead to a derivative of tetrahydrofuran or tetrahydropyran, the former exclusively formed. The regioselectively for such reaction is 100%. When R1 or R2 = CH3, among the diasteroisomeric products trans predominates over cis. In this cyclization reaction titanium silicate epoxidizes the olefin and successively catalyzes the opening of the oxirane ring via intramolecular attack of hydroxy oxygen. Thus the behavior of titanium sites is bifunctional in nature. However, for bicyclic unsaturated alcohols, because of geometric restriction, activity of medium pore TS-1 is very low. Ti-beta synthesized by dry gel conversion has been found to be an efficient catalyst in oxidative cyclization of such bulky organic substrates as α-terpineol, isopulegol, and trans-p-menth-6-ene-2,8-diol to their corresponding tetrahydrofuranols or tetrahydropyranols with a very high regioselectivity.
TRANSPOSITION DES OXIRANNES-ETHANOLS PAR L'INTERMEDIAIRE D'ALCOXYETAINS. INFLUENCE DE LA CONFIGURATION DE L'OXIRANNE
Bats, J.-P.,Moulines, J.,Picard, P.,Leclerq, D.
, p. 3051 - 3054 (2007/10/02)
The transposition of oxirane-ethanols, through alkoxytin compounds, into oxetane-2-methanols and/or oxolan-3-ols (tetrahydrofuran-3-ols) is dependent upon the oxirane configuration.Cis configuration is more suitable for the formation of the smallest ring.Steric hindrance is not sufficient enough to explain the results.
