Cross coupling of silylphosphines with 2-halobenzenecarboxylates or 2-halophenyl ethers, catalyzed with zero-valent palladium complexes can not be used as a procedure for preparing sterically hindered tertiary phosphines. The latter compounds can be successfully prepared by means of phosphorylation of corresponding o-lithiated derivatives.In [1], a procedure for preparing secondary alkyl-(aryl)phosphines of the general formula RArPH containing electron-donor and electron-acceptor substituents in the aromatic ring have been proposed. This procedure is based on cross coupling of alkyl-(trimethylsilyl)phosphines with corresponding aryl halides in the presence of catalytic amounts of zerovalent palladium.In this work we have studied the cross coupling of trimethylsilyl derivatives of secondary phosphines R 1 R 2 PSiMe 3 Ia and Ib [R 1 = i-Pr, R 3 = tert-Bu (a); R 1 = tert-Bu, R 2 = Ph (b)] and also of bis-silylated primary phosphines RP(SiMe 3 ) 2 IIa and IIb [R = i-Pr ÄÄÄÄÄÄÄÄÄÄÄÄ (a); R = tert-Bu (b)] with various aryl halides YC 6 H 4 Hlg III [reactions (1) and (2)] with the purpose to establish the utility of the above procedure for preparing tertiary alkyl(aryl)phosphines R 1 R 2 PC 6 H 4 Y IV and RP(C 6 H 4 Y) 2 V with secondary and tertiary alkyl groups and a series of o-and m-substituents in the aromatic ring. Bulky radicals in phosphines IV and V, including o-substituted in the aromatic ring, were chosen to impart configurational stability to racemic tertiary phosphines which we proposed to resolve into optical antipodes [2]. Substituents containing alkoxycarbonyl groups were introduced to render the synthesized phosphine ligands water-soluble after hydrolysis. R 1 R 2 PSiMe 3 + 4 c = Y Hlg 7777776 3Me 3 SiHlg 235 mol% Pd(0), to 4 c = Y PR 1 R 2 I III IV R(PSiMe 3 ) 2 + 2III 7777776 3Me 3 SiHlg 235 mol% Pd(0), to 4 c = Y PR 2 V II (1) (2) ÄÄÄÄÄÄÄÄÄÄÄÄIt was previously reported that the aromatic functionally substituted tertiary phosphines are successfully prepared by cross coupling of bromo(iodo)arenes III with diphenyl(trimethylsilyl)phosphine [3] and even with diphenylphosphine [4,5], whereas tertiary phosphines with bulky alkyl groups and functional groups in the aromatic ring were not obtained.Preliminary experiments showed [1] that the synthesis of tertiary phosphines by reaction (2) requires much more rigid conditions (1303140oC) than the synthesis of secondary phosphines (503100oC), and the slowest reactions are observed with o-substituted haloarenes III. In view of these results, we primarily studied the cross coupling of bis-silylphosphines IIa and IIb with bromide IIIa (Y = 3-CF 3 ) which was expected to be the most resistant to bromo-and especially iodotrimethylsilane evolved upon prolonged heating of the components of reaction (2). Reactions (1) and (2) were carried out in sealed ampules with