Organophosphorus Chemistry: Volume 20 (Specialist Periodical Reports, Volume 20),Used

Excerpt. Reprinted by permission. All rights reserved. Organophosphorus Chemistry Volume 20A Review of the Literature published between July 1987 and June 1988By B. J. Walker, J. B. HobbsThe Royal Society of ChemistryCopyright 1989 The Royal Society of ChemistryAll rights reserved.ISBN: 9780851861869ContentsCHAPTER 1 Phosphines and Phosphonium Salts By D.W. Allen, CHAPTER 2 Pentacoordinated and Hexacoordinated Compounds By C.D. Hall, CHAPTER 3 Phosphine Oxide and Related Compounds By B.J. Walker, CHAPTER 4 Tervalent Phosphorus Acids By O. Dahl, CHAPTER 5 Quinquevalent Phosphorus Acids By R.S. Edmundson, CHAPTER 6 Nucleotides and Nucleic Acids By J.B. Hobbs, CHAPTER 7 Ylides and Related Compounds By B.J. Walker, CHAPTER 8 Phosphazenes By C.W. Allen, AUTHOR INDEX, 353, CHAPTER 1Phosphines and Phosphonium SaltsBY D. W. ALLEN1 Phosphines1.1 Preparation1.1.1 From Halogenophosphines and Organometallic Reagents. Grignard reagents derived form chloromethyl ethers have been used in the synthesis of the alkoxymethylphosphines (1). A series of phosphine ligands bearing a siliconcontaining backbone, e.g.. (2), has been prepared by the reactions of chlorodiphenylphosphine with Grignard reagents derived from a haloalkylsilanes. Sequential alkylation of aryldichlorophosphines has been achieved using bulky Grignard reagents, giving rise to chiral phosphines, e.g. (3), in good yield. Grignard procedures have also been employed in the synthesis of chiral phosphines, e.g. (4), derived from the a pinene system, the substituted thienylphosphines (5), and the 14Clabelled phosphine (6). The reaction of methylmagnesium halides with phosphite esters in ether affords a route to high purity trimethylphosphine.The generation of organolithium reagents by the metallation of readily available substrates using butyllithium or lithium diisopropylamide continues to be a popular strategy for the synthesis of unusual phosphines. Metallation of acetonitrile affords cyanomethyllithium, which on treatment with chlorodiorganophosphines gives the cyanomethylphosphines (7). Treatment of bis(cyclopentadienyl)chromium with butyllithium, in the presence of TMEDA, results in the formation of the 1,1' dilithio derivative which, with tetramethyldiphosphine, results in the new bidentate ligand (8). Two more reports have appeared of the synthesis of 10phenylphenoxaphosphine (9) based on the direct dimetallation of diphenyl ether. Full details have now appeared of the synthesis of tris and tetrakis (diphenylphosphino)allenes (10), based on the reaction of chlorodiphenylphosphine with the product of metallation of diphenylpropynylphosphine in the presence of butyllithium. In a similar vein, metallation of 1,1dimethylallene using lithium diisopropylamide is the key step in the synthesis of the monophosphinoallene (11). Subsequent metallation of (11) at carbon adjacent to phosphorus, using butyllithium, affords a route to the geminal bis(phosphino)allene (12). Organolithium reagents derived from the appropriate 6,6' disubstituted 2,2' dibromobiphenyl have been employed in the synthesis of the chiral diphosphines (13), which have been resolved via the use of chiral palladium complexes. The reaction of olithiophenyldimethylphosphine with triphenylphosphite has given the tetradentate phosphine ligand (14). A simple route to tris(trimethylsilyl)phosphine is afforded by the reaction of N(dichlorophosphino)piperidine with lithium and chlorotrimethylsilane.Organolithium reagents, Grignard reagents, and, an unusual alternative, the trimethylsilyl derivatives of heterocyclic systems, have been used to convert bis(dichlorophosphino)methane and ethane into a variety of new, chelating, diphosphine ligands, e.g.. (15). The reaction of the sodium enolate of ethyl acetate with isopropyldichlorophosphine provides a route to the phosphinocarboxylate ester (16), and hence, by hydrolysis, the corresponding phosphinodicarboxylic acid. Such compounds, involving bu