Département de chimie moléculaire

Tert-Bu thiol, 2,6-dimethylthiophenol, 2,6-dimethylphenol, and 2,6-bis(tert-butyl)-4-methylphenol cleanly add to the 1$\sigma$4,3$\sigma$2-diphosphacumulene (1; (iPr2N)2ClP:C:P(NiPr2)) to afford the corresponding C-phosphino P ylides (2a-d; (iPr2N)2ClP:CHP(NiPr2)(R); R = StBu, SC6H3Me2-2,6, OC6H3Me2-2,6, OC6H2tBu2-2,6-Me-4). Treatment of 2a with GaCl3 quant. leads to the C-phosphonio phosphaalkene 3, resulting from the 1,3-migration of the sulfido group. Under the same exptl. conditions, cleavage of the arylthio and aryloxy groups of 2b and 2c leading to the C-phosphonio phosphaalkene 4 is obsd. In the case of the sterically most crowded deriv., 2d, abstraction of the chloride ion affords the 1$\sigma$3,3$\sigma$3-diphosphaallyl cation, (5; [(iPr2N)2P+:CHP(NiPr2)(OC6H2tBu2-2,6-Me-4)][GaCl4]), which is stable for several weeks in CH2Cl2 at -20°, but decomps. after a few minutes at {\textgreater}0°. Compd. 5 reacts at low temps. with an excess of MeCN or benzaldehyde to afford quant. and regioselectively the corresponding five-membered heterocycles, 6 and 7. The NMR spectroscopy data and reactivity suggest that 5 features a localized double bond with a planar diamino-substituted P center, and a single bond with a pyramidalized (amino)(aryloxy)phosphino group. [on SciFinder(R)]