[3+2] Cycloaddition reactions of diethyl (E)-2-fluoromaleate
摘要:
Diethyl E-2-fluoromaleate has been prepared in a pure state in 89% yield by a Horner-Wadsworth-Emmons Wittig procedure. The E configuration was determined by NMR spectroscopy. Diethyl E-2-fluoromaleate undergoes [3+2] cycloadditions with a series of aromatic alpha-iminoesters and aromatic nitrones. The yields of purified cyclic products ranged from 65 to 80%. (C) 2012 Elsevier B.V. All rights reserved.
Synthesis of Small 3-Fluoro- and 3,3-Difluoropyrrolidines Using Azomethine Ylide Chemistry
摘要:
Here, we report accessing small 3-fluoropyrrolidines and 3,3-difluoropyrrolidines through a 1,3-dipolar cycloaddition with a simple azomethine ylide and a variety of vinyl fluorides and vinyl difluorides. We demonstrate that vinyl fluorides within alpha,beta-unsaturated, styrenyl and even enol ether systems can participate in the cycloaddition reaction. The vinyl fluorides are relatively easy to synthesize through a variety of methods, making the 3-fluoropyrrolidines very accessible.
The study of the Julia–Kocienski reaction between fluorinated arylsulfone and ketones is described. The corresponding fluoroalkenes were isolated in moderate to good yields from β- and δ-substituted cyclic ketones. From acyclic ketones and α-substituted cyclic ketones a decarbethoxylation reaction of the sulfonylesters occurred. This decarbethoxylation reaction opened a new route for the preparation