Methyl 3-substituted-isoxazole-5- carboxylates syntheses on solid supports via wang resin-bound 2,3-dibromopropionate
作者:Shou-Ri Sheng、Ai-Ying He、Mei-Hong Wei、Ai-Li Zhu、Ming-Zhong Cai
DOI:10.1002/hc.21035
日期:——
A novel Wangresin-bound2,3-dibromopropionate reagent has been developed and used as a potential dipolarophile for the facile preparation of methyl 3-substituted-isoxazole-5-carboxylates through triethylamine, promoting a sequence of reactions involving the in situ generation of 2-bromoacrylate resin and nitrile oxide, regioselective 1,3-dipolar cycloaddition, and loss of hydrogen bromide in one pot
DFT-HSAB Prediction of Regioselectivity in 1,3-Dipolar Cycloadditions: Behavior of (4-Substituted)benzonitrile Oxides towards Methyl Propiolate
作者:Alessandro Ponti、Giorgio Molteni
DOI:10.1002/chem.200500739
日期:2006.1.23
The regioselectivity of 1,3-dipolarcycloadditions between (4-substituted)benzonitrileoxides and methyl propiolate cannot be rationalized on the basis of the electron demand of the reactants or frontier molecular-orbital theory. To this problem, we have applied a quantitative formulation of the hard-soft acid-base principle developed within the density functional theory. Global and local reactivity