Anomeric effect enhancement in C-5-substituted 2-methoxytetrahydropyrans
摘要:
cis- and trans-2,5-Dimethoxytetrahydropyrans, cis-2,5-dimethoxy-6-methyltetrahydropyran and 2-methoxy-5-methyltetrahydropyran have been examined to see the effect of an OCH3 group at position 5 on the degree of anomeric effect in substituted 2-methoxytetrahydropyrans. The present study shows that this group stabilises the C-2 electronegative substituent in the axial position. Semi-empirical and ab initio molecular orbital calculations support this view. AM1 calculation gives lower enthalpies as well as lower dipole moments for the compounds having an OCH3 group in the axial position at C-2 over the equatorial form in 2-methoxytetrahydropyrans. This enhanced stabilisation is attributed to the electrostatic interaction between the partial positive charge at C-5 and the partial negative charge of the aglycone oxygen atom. (C) 1997 Elsevier Science B.V.
Production Process Of Tetrahydropyran Compound And Tetrahydropyran Compound Produced By The Production Process
申请人:Yamagami Isao
公开号:US20080139828A1
公开(公告)日:2008-06-12
The invention provides a production, process of a tetrahydropyran compound, characterized by allowing 3,4-dihydro-2-alkoxy-2H-pyran compound or tetrahydro-2-alkoxy-2H-pyran compound which can be easily prepared through reaction between acrolein and alkylvinylether, with hydrogen in the presence of a catalyst containing an element of Groups VIII to X under acidic condition. The production process of the invention is useful for production of Grignard reaction solvent or polymer solvent and intermediate of organic compound.