Organophosphorus Chemistry: Volume 18 (Specialist Periodical Reports - Organophosphorus Chemistry)

Product description Excerpt. © Reprinted by permission. All rights reserved. Organophosphorus Chemistry Volume 18A Review of the Literature published between July 1985 and June 1986By B. J. WalkerThe Royal Society of ChemistryCopyright © 1987 The Royal Society of ChemistryAll rights reserved.ISBN: 978-0-85186-166-1ContentsCHAPTER 1 Phosphines and Phosphonium Salts By D.W. Allen, CHAPTER 2 Pentaco-ordinated and Hexaco-ordinated Compounds By C.D. Hall, CHAPTER 3 Phosphine Oxides 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, CHAPTER 9 Physical Methods By J.C. Tebby, AUTHOR INDEX, 425, CHAPTER 1Phosphines and Phosphonium SaltsBY D. W. ALLEN1 Phosphines1.1 Preparation1.1.1 From Halogenophosphines and Organometallic Reagents.- A greatly improved route to tris-t-butylphosphine is afforded by the addition of a benzene solution of phosphorus trichloride to a pentane solution of t-butyllithium. Direct metallation of benzenechromiumtricarbonyl with butyllithium at -30 °C, followed by treatment with chlorodiphenylphosphine, provides a more direct route to diphenylbenchrotenylphosphine (1). The reactions of pentadienyllithium with halogenophosphines have given a series of pentadienylphosphines, e.g. (2), isolated as the corresponding oxides after treatment with hydrogen peroxide. Lithiation of o-bromophenyldimethylarsine with butyllithium, followed by treatment with phosphorus trichloride, gives the new polydentate ligand (3), but in only 15% yield. The reaction of the α-diazomethyllithium reagent (4) with chlorodi(isopropylamino)-phosphine leads to the first α-diazomethylphosphine, (5), which is stable to distillation. Photolysis of (5) generates the phosphinocarbene (6), which is found to be more stable than might have been expected, behaving either as a phosphorus vinyl ylide or as a λ5-phospha-acetylene. The heterocyclic systems (7) are formed in the reactions of triphenylsilyllithium with the corresponding heterocyclic chlorophosphines.Conventional aryl Grignard procedures have been used in the synthesis of the new phosphines (8), (9) and (10). The reactions of chlorodiphenylphosphine with Grignard reagents derived from chloromethylsilanes have given a range of phosphines bearing a silicon-containing substituent or back-bone, e.g. (11). The trideritate phosphine ligand (12; R = Me) is formed on treatment of the precursor halogenophosphine (12; R = Cl) with an excess of methylmagnesium chloride. The reactions of the unsaturated dichloro(amino)phosphine (13) with a range of alkyl Grignard reagents give rise to a mixture of the rearranged phosphines (14) and (15).1.1.2 Preparation of Phosphines from Metallated Phosphines.- It has been shown that phosphide anions may be generated from primary and secondary phosphines under aqueous conditions using concentrated aqueous alkali in DMSO or other dipolar aprotic solvents. Alkylation of the resulting anions has given a range of secondary and tertiary phosphines.The generation of the bismetallophosphide reagents (16) by lithium-induced cleavage of phenyl groups from α,ω-bis(diphenylphosphino)alkanes is greatly facilitated by irradiation with ultrasound. The direction of the lithium-induced cleavage of the heterocyclic diphosphine (17) depends on the nature of the non-phosphorus substituents. When R = Ph, P-P cleavage takes place, whereas when R = But, cleavage of an exocyclic phenyl group occurs, resulting in the formation of the cyclic anion (18), which undergoes the expected protonation and alkylation reactions at phosphorus on subsequent treatment with electrophilic reagents. Treatment of 2,4-bis(chloromethyl)pyrazolium salts with lithium diphenylphosphide affords the pyrazolyldiphosphine (19), which is found to be very easily oxidised by air and is therefore stored in the form of a nickel complex from which it can be freed by cyanide ion. The reaction of the dilithiodiphosphide (20) with white phosphorus generates the lithiophosphide (21) derived from the 2,3-dihydro-1H-benzotriphosphole system. The [2+1] cyclocondensation of 1,2-dichloropropane with dilithium t-butylphosphide yields the surprisingly stable phosphirane (22).Baudler's group has continued to investigate the uses of inorganic polyphosphides, e.g. Li3P7 and Li2P16, in the synthesis of polycyclic organophosphines of ever-increasing complexity. In related work, the first bicyclo[3,2,0]heptaphosphine, P7But5, (23), has been isolated from the reaction of butyldichlorophosphine, phosphorus trichloride, and magnesium. The reactions of various lithium phosphides with dichlorodiorganosilanes have given a range of cyclic silylphosphines. The four-membered ring system (24), isolated in 76%, yield in the reaction of monolithium phosphide with di-t-butyldichlorosilane, has bee