Stereoselective Cycloadditions of Pyridinium or Isoquinolinium Methylides with Olefinic Dipolarophiles and Subsequent Cycloadditions of the Cycloadducts with Nitrile Oxides
作者:Otohiko Tsuge、Shuji Kanemasa、Shigeori Takenaka
DOI:10.1246/bcsj.59.3631
日期:1986.11
Pyridinium or isoquinolinium methylides undergo highly stereo- and regioselective cycloadditions with olefinic dipolarophiles to form unstable tetrahydroindolizine derivatives. One of the two double bonds existing in the dihydro heteroaromatic ring of the cycloadducts reacts with nitrile oxides, in the same flask, in stereo-, regio-, and periselective fashions to lead to stable isoxazole-fused tetrahydroindolizines
Acid-catalyzed elimination of pyridine from the stereoselective [3+2] cycloadducts between electron-deficient olefins and pyridinium methylides with ylide-stabilizing substituents offers a new type of C–C bond formation.