Catalysis of Intramolecular Morita-Baylis-Hiliman and Rauhut-Currier Reactions by Fluorous Phosphines; Facile Recovery by Liquid/Solid Organic/Fluorous Biphase Protocols Involving Precipitation, Teflon (R) Tape, and Gore-Rastex (R) Fiber
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
The fluorous phosphine P[(CH2)3Rf8] 3 [1, Rf8=(CF2)7CF3; 10 mol%] catalyzes intramolecular Morita-Baylis-Hillman reactions of O=CH-(CH 2)nCH=CH(C=O)R [n/R=2/Ph (2a), 2/S-i-Pr, 3/p-tol] in acetonitrile at 60-72C. Upon cooling, 1 precipitates and is recycled. The products HOCH(CH2)nCH=C(C=O)R are isolated from the supernatant (78-96%). The educt i-PrS(C=O)CH=CH(CH2) 2CH=CH(C=O)S-i-Pr similarly undergoes a Rauhut-Currier reaction to give i-PrS(C=O)CH2CH(CH2)2CH=C(C=O)S-i-Pr (71-73%). In the case of 2a, reactions are also conducted in the presence of Teflon tape or Gore-Rastex fiber. The catalyst now precipitates onto the fluoropolymer support, mechanically facilitating recycling. For each reaction, three to five cycles are conducted. HPLC or GC monitoring of the rates show low activity losses, with Gore-Rastex fiber giving better results than Teflon tape, presumably due to a higher surface area. 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
