Synthesis, properties, and reactions of enantiomerically pure, chiral fluorous phosphines of the formula (menthyl)P(CH2CH2(CF2)n-1CF3)2 (n=6, 8)

Reactions of (menthyl)PH2 and H2C=CHRf6 (menthyl=1R,3R,4S; R-fn=(CF2)(n-1)CF3) or H2C=CHRf8 (AIBN, refluxing THF) give (menthyl)PH(CH2CH2Rfn) and then (menthyl)P(CH2CH2Rfn)(2) (n=6, 7; n=8, 8), but with purification or other difficulties at each stage. Reactions of (menthyl)PCl2 with IMgCH2CH2Rfn give, under careful conditions, analytically pure 7 or 8 in 28-32% yields after distillation. Some R-fn(CH2)(4)R-fn also form. These represent the first chiral (and non-racemic) fluorous phosphines. Reactions of 7 or 8 with [Ir(COD)Cl](2) and CO give trans-[(menthyl)P(CH2CH2Rfn)(2)]Ir(CI)(CO) (n=6, 71%; 8, 51%) as analytically pure yellow oils. Their IR vco values show the donor/acceptor properties of 7 and 8 to be intermediate between those of P((CH2)(3)R-f8)(3) and P((CH2)(4)R-f8)(3) The CF3C6F11 :toluene partition coefficients of 7 and 8 (27 degrees C, 78.4:21.6 and 93.7:6.3) are distinctly lower than those of P((CH2)(2)R-fn)(3) (n=6, 98.8:1.2; n=8, >99.7:<0.3), reflecting the replacement of a linear Cs-8-C-10 group that is ca. 75-80% fluorinated by a cyclic C-10 terpenyl group. Reactions of 7 or 8 with [Rh(COD)Cl](2) give [(menthyl)P(CH2CH2Rfn)(2)]Rh(Cl)(COD) (n=6, 69%; 8, 70%) as orange crystallizable oils. (C) 1999 Elsevier Science Ltd. All rights reserved.