‘Phospha-Wittig’ reactions using isolable phosphoranylidenephosphines ArPPR3 (Ar = 2,6-Mes2C6H3 or 2,4,6-But3C6H2)

The Substituent Effect of the Phosphaalkenyl Group

“…[3Ϫ5] This observation holds for the unsubstituted parent compound 6f [20Ϫ23] and for 6a, [21Ϫ23] 6b, [22] 6c, [21,22,24] 6d, [23] 6g, [23] 6h, [22] 6i, [22,24] 6j, [22] and 6o. [24] Using the method of Yoshifuji et al, [20] we obtained 6j and 6n in a one-pot procedure by conversion of Mes*PH 2 (9) via the silyl derivative 10 into its lithio derivative 11, which was treated with p-bromo-or p-cyanobenzaldehyde to furnish 6j or 6n, respectively, in yields of 90Ϫ95% (Scheme 4).…”

“…[24] Using the method of Yoshifuji et al, [20] we obtained 6j and 6n in a one-pot procedure by conversion of Mes*PH 2 (9) via the silyl derivative 10 into its lithio derivative 11, which was treated with p-bromo-or p-cyanobenzaldehyde to furnish 6j or 6n, respectively, in yields of 90Ϫ95% (Scheme 4). This reaction was stereospecific in providing the (E) isomer exclusively.…”

2,3,5,6‐Tetrafluoro‐p‐phenylenebis(phosphanes) – Preparation and Structure of an Electron‐Poor P–RF–P Linker

“…[24,25] A general route towards the synthesis of dichlorophosphanes includes the reaction of the corresponding R-M (M = Li or MgBr; R = organic substituent) compound with an excess of PCl 3 , if steric protection of R is sufficient to prevent multiple substitution at the phosphorus atom. Recently, we investigated the reaction of 2,3,5,6-F 4 C 6 HLi with PCl 3 and observed the formation of a mixture of multiplesubstituted phosphanes [PCl n (C 6 F 4 H) 3-n ] even if a 10-fold excess of PCl 3 was used. [26] To circumvent this problem, we treated the "protected" chlorobis(diethylamino)phosphane ClP(NEt 2 ) 2 with 2,3,5,6-F 4 C 6 Li 2 at a low temperature.…”

“…In the last decades general synthetic routes to diphosphenes, [1] iminophosphanes, [2] phosphaalkenes [3,4] and phospholes [5] have been established, which employ dichlorophosphanes as [P + ] synthons. The parent p-phenylenebis(dichlorophosphane) has been prepared in 1962, [6] and the 2,3,5,6-tetramethyl- [7] and -tetraaryl-substituted [4] congeners later on.…”

Hydride Abstraction and Deprotonation – an Efficient Route to Low Coordinate Phosphorus and Arsenic Species

“…Transition metal stabilised phosphanylidene-σ 4 -phosphoranes (R 3 P=P(R)→ML n ) were first synthesised by Mathey and co-workers in 1990 [1] and have received attention as "phosphaWittig" reagents for the generation of P=C bonds, in which they act as phosphinidene (R-P) transfer reagents. [2][3][4][5][6] Free phosphanylidene-σ 4 -phosphoranes are rather reactive species, with only a handful of published examples where the compound is stabilised by extremely electron withdrawing substituents, [7,8] steric shielding, [9][10][11] or the combination of a rigid backbone and steric shielding. [12] Low co-ordinate arsenic chemistry is significantly less studied than that of phosphorus, with most attention being focused on arsaalkenes (R 2 C=AsR'), diarsenes (RAs=AsR), [13][14][15][16] and phosphine-and carbene-stabilised cationic species.…”