Nitrile Oxide [3 + 2] Cycloaddition: Application to the Synthesis of 6-Substituted 3(2H)-Pyridazinones and 6-Substituted 4,5-Dihydro-4-hydroxy-3(2H)-pyridazinones
An Improved Method for Preparation of Nitrile Oxides from Nitroalkanes for In Situ Dipolar Cycloadditions
作者:Yochai Basel、Alfred Hassner
DOI:10.1055/s-1997-1181
日期:1997.3
A new method has been found for generation of nitrile oxides in situ from nitroalkanes under mild conditions. Thus, reaction of nitroalkanes 1 with di-tert-butyl dicarbonate (2) and 4-dimethyl-aminopyridine (3) as catalyst in the presence of dipolarophiles at room temperature afforded cycloadducts (e.g. 5,6, and 7) in improved yields compared to known methods. Solvent effects were also noted.
A method for generating nitrile oxides from nitroalkanes: a microwave assisted route for isoxazoles
作者:Giampaolo Giacomelli、Lidia De Luca、Andrea Porcheddu
DOI:10.1016/s0040-4020(03)00859-7
日期:2003.7
A convenient route has been developed for generation of nitrileoxides in situ from nitroalkanes under very mild conditions using microwave irradiation, using 4-(4,6-dimethoxy[1,3,5]triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) and DMAP as catalyst. Isoxazolines and isoxazoles are obtained in very good yields compared to known methods.
A practical and safe reduction methodology for the conversion of Î2-isoxazolines to 1,3-aminols is developed using polymethylhydrosiloxane-Pd(OH)2/C. In presence of (Boc)2O, the isoxazoline was converted into N-Boc protected 1,3-aminol in a one-pot procedure.
Resolution of ?2-isoxazoline-5-carboxylates by a protease fromAspergillus Oryzae providing masked synthons for enantiopure ?-aminoalcohols and related structures
作者:S. Yang、W. Hayden、H. Griengl
DOI:10.1007/bf00811865
日期:1994.4
A series of racemic DELTA2-isoxazolinecarboxylates have been synthesized and subjected to enzymatic hydrolysis by a protease from Aspergillus oryzae in a two-phase system. Out of these compounds only isoxazoline-5-carboxylates unsubstituted at C-4 were hydrolyzed. Thus, from 3-ethoxycarbonyl-, 3-methyl-, and 3-phenyl-DELTA2-isoxazoline-5-carboxylates the corresponding (R)-configurated carboxylic acids are obtained. In contrast, an additional methyl group at C-5 changes the steric course of the hydrolysis to give predominantly the (S)-acid. The enantioselectivities obtained are in the range of E = 5-35.
FURUKAWA, ISAO;NISHIOKA, YOSHIHIRO;HASHIMOTO, SHIZUNOBU, SCI. AND ENG. REV. DOCHISHA UNIV., 1983, 24, N 1, 69-77