Synthesis and properties of fluorous arenes and triaryl phosphorus compounds with branched fluoroalkyl moieties (“split pony tails”) |
| |
Authors: | Marc Wende |
| |
Affiliation: | Institut für Organische Chemie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestraße 42, Erlangen 91054, Germany |
| |
Abstract: | Most compounds designed for immobilization in fluorous media feature linear pony tails of the formula (CH2)m(CF2)n−1CF3 [(CH2)mRfn]. This paper presents a first-generation approach to compounds with branched or “split” pony tails of the formula (CH2)lCH[(CH2)mRfn]2. Allyl tri(n-butyl)tin is reacted twice with perfluorooctyl iodide (Rf8I; first, photochemical, 78-81%; second, thermal with radical initiator, 71%; 13-18 g scales) to give the secondary alkyl iodide ICH(CH2Rf8)2 (3). A subsequent Ni(Cl)2(PPh3)2-catalyzed reaction with allyl tri(n-butyl)tin yields the branched alkene H2CCHCH2CH(CH2Rf8)2 (74%). A palladium-catalyzed Heck coupling with OP(p-C6H4Br)3 gives the fluorous phosphine oxide OP(p-C6H4CHCHCH2CH(CH2Rf8)2)3 (84%), and Pd/C-catalyzed hydrogenation affords OP(p-C6H4(CH2)3CH(CH2Rf8)2)3 (>99%). Reduction with SiHCl3 gives P(p-C6H4(CH2)3CH(CH2Rf8)2)3, which is protected as the air-stable borane adduct H3B·P(p-C6H4(CH2)3CH(CH2Rf8)2)3 (9, 64%). The CF3C6F11/toluene partition coefficient of 9 is much higher than that of the analog with p-(CH2)3Rf8 groups (96.6:3.4 versus 37.3:62.7). The iodide 3 is unreactive towards PAr3 at 175-250 °C. However, a CuBr-catalyzed reaction with C6H5MgBr gives C6H5CH(CH2Rf8)2, which also exhibits a high partition coefficient (97.9:2.1). |
| |
Keywords: | Fluorous Tin Radical substitution Radical addition Heck reaction Phosphine-boranes |
本文献已被 ScienceDirect 等数据库收录! |
|