No abstract

2-(Trifluoromethyl)allyl ketone O-pentafluorobenzoyloximes undergo a palladium-catalyzed 5-endo mode of alkene insertion via oxidative addition of the N-O bond, followed by beta-fluorine elimination to produce 4-difluoromethylene-1-pyrrolines.

Pyrrole derivatives R 0120 5-endo Heck-Type Cyclization of 2-(Trifluoromethyl)allyl Ketone Oximes: Synthesis of 4-Difluoromethylene-Substituted 1-Pyrrolines. -Title compounds (I) undergo a Pd-catalyzed 5-endo mode of alkene insertion via oxidative addition of the N-O bond, followed by β-fluorine elimination to produce 4-difluoromethylene-1-pyrrolidines (II). Interestingly, no β-hydrogen elimination and formation of trifluoromethyl-pyrazoles is observed. -(ICHIKAWA*, J.; NADANO, R.; ITO, N.; Chem. Commun. (Cambridge) 2006, 42, 4425-4427; Dep. Chem., Fac. Sci., Univ. Tokyo, Bunkyo, Tokyo 113, Japan; Eng.) -M. Paetzel 11-093

Ring closure reactions O 0130Heck-Type 5-endo-trig Cyclizations Promoted by Vinylic Fluorines: Ring-Fluorinated Indene and 3H-Pyrrole Syntheses from 1,1-Difluoro-1-alkenes. -The 5-endo-trig alkene insertion in the Heck-type cyclization of aryl triflate (II) and oximes (XI) is accomplished by taking advantage of the polarized double bond in the difluoroalkene part. In both systems, the two vinylic fluorine atoms are essential for the cyclization. The unusual alkene insertion followed by β-fluorine elimination enables the synthesis of ring-fluorinated indene (III) and 3H-pyrroles (XII) as well as the construction of the fused tricyclic system (XIV). -(ICHIKAWA*, J.; SAKODA, K.; MIHARA, J.; ITO, N.; J. Fluorine Chem. 127 (2006) 4-5, 489-504; Dep. Chem., Grad. Sch. Sci., Univ. Tokyo, Bunkyo, Tokyo 113, Japan; Eng.) -H. Hoennerscheid 38-042