Reaktive E=C(p-p)π-Systeme, XXVIII / Reactive E=C(p-p)π-Systems, XXVIII

Abstract

The reaction of perfluoro-2-phosphapropene F3CP=CF2 (1) with tert-butylamine or isopropylamine in a 1:3 molar ratio leads to the novel iminomethylene phosphanes F3CP=C=N(tBu) [(2), 30% yield] and F3CP=C=N(iPr) [(3), 5%], respectively. 2 slowly decomposes at room temperature giving tert-butylisonitrile and the cyclophosphanes (F3CP)n (n = 3, 4, 5). 3 is found to be less stable than 2 and for example is attacked by primary amines. The reaction of 2 with 2,3-dimethyl-1,3-butadiene or trimethylphosphane yields, on the one hand, the cycloaddition product of bis(trifluormethyl)diphosphene (4), and on the other hand, the phosphorus ylid Me3P=PCF3 (5) together with (tBu)NC. 2 and 3, respectively, are not obtained from (F3C)2PH and the corresponding primary amines in a series of HF elimination and H2NR addition reactions. The main products formed from a 1:4 molar mixture of (F3C)2PH and H2N(iPr) in a one-pot procedure were shown to be the chiral phosphanes F3CP[NH(iPr)]C[=N(iPr)]H (6), F3CP[NH(iPr)]CHF2 (7) and F3CP[NH(iPr)]CH2F (8) (60:35:5). The corresponding reaction of (F3C)2PH with H2N(tBu) mainly yields the compound F3CP[NH(tBu)]CH2F (10).