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Trimethylsilyl‐ and Trimethylstannyldimethylphosphane—Convenient and Versatile Reagents for the Synthesis of Polyfluoroaryldimethylphosphanes
Author(s) -
Goryunov Leonid I.,
Grobe Joseph,
Shteingarts Vitalij D.,
Krebs Bernt,
Lindemann Arno,
Würthwein ErnstUlrich,
MückLichtenfeld Christian
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20001215)6:24<4612::aid-chem4612>3.0.co;2-7
Subject(s) - reagent , phosphide , chemistry , trimethylsilyl , hydride , fluorine , substrate (aquarium) , solvent , benzene , medicinal chemistry , single crystal , crystallography , organic chemistry , hydrogen , catalysis , oceanography , geology
Trimethylsilyldimethylphosphane (Me 3 SiPMe 2 ) and the corresponding tin compound (Me 3 SnPMe 2 ) were used as reagents for the substitution of fluorine by the Me 2 P group in polyfluoroarenes C 6 F 5 X (X=F, H, Cl, CF 3 ) and C 5 NF 5 . The reactions occur even under mild conditions ( T =0–20 °C), either in benzene or without solvent, to give as a rule 4‐X‐1‐(dimethylphosphano)tetrafluorobenzenes (XC 6 F 4 PMe 2 , 1 – 4 ) and 4‐(dimethylphosphano)tetrafluoropyridine (C 5 NF 4 PMe 2 , 5 ), respectively, in yields between 75 and 95 %. In the case of C 6 F 6 , double substitution is also observed, which affords 1,4‐bis(dimethylphosphano)tetrafluorobenzene ( 6 ). A very efficient route to the compounds XC 6 F 4 PMe 2 (X=F, H, Cl, CF 3 ) and C 5 NF 4 PMe 2 was developed as a one‐pot reaction of the corresponding fluoroarenes with tetramethyldiphosphane (P 2 Me 4 ) and trimethyltin hydride (Me 3 SnH) at moderate temperatures. This process was tested for C 6 F 6 and perfluorobiphenyl which gave C 6 F 5 PMe 2 ( 1 ) and 4,4′‐bis(dimethylphosphano)octafluorobiphenyl ( 7 ), respectively. The results, which included kinetic measurements that used the intensities of the 31 P signals, revealed the influence of the substrate type on the rate of reaction in the sequence: C 5 NF 5 >C 6 F 5 CF 3 >C 6 F 5 Cl, C 6 F 5 PMe 2 >C 6 F 5 H>C 6 F 6 ≫C 6 H 5 F. Ab initio calculations were carried out on the model reactions of pentafluoropyridine with silylphosphane, phosphane or phosphide to discriminate between possible reaction mechanisms. The novel phosphanes were characterised by spectroscopic investigations (NMR, MS), by preparation of the related thiophosphanes Ar F P(=S)Me 2 ( 8 – 14 ), their spectroscopic and analytic data and single crystal X‐ray diffraction studies on five of these derivatives.