Phenylphosphatrioxa-adamantanes: bulky, robust, electron-poor ligands that give very efficient rhodium(I) hydroformylation catalysts.

The cage phosphines 1,3,5,7-tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane (1a) and 1,3,5,7-tetraethyl-6-phenyl-2,4,8,trioxa-6-phosphaadamantane (1b) have been made by the acid catalysed addition of PhPH(2) to the appropriate beta-diketones; the acid used (HCl, H(3)PO(4) or H(2)SO(4)) and its concentration affect the rate and selectivity of these condensation reactions. Phosphines 1a and 1b react with [PdCl(2)(NCPh)(2)] to form complexes trans-[PdCl(2)(1a)(2)](2a) and trans-[PdCl(2)(1b)(2)](2b) as mixtures of rac and meso diastereoisomers. The platinum(II) chemistry is more complicated and when 1a or 1b is added to [PtCl(2)(cod)], equilibrium mixtures of trans-[PtCl(2)L(2)] and [Pt(2)Cl(4)L(2)](L = or ) are formed in CH(2)Cl(2) solution. Meso/rac mixtures of trans-[MCl(CO)(1a)(2)] M = Ir (6a) or Rh (7a) are formed upon treatment of MCl(3).nH(2)O with an excess of 1a and the anionic cobalt complex [NHEt(3)][CoCl(3)(1a)](9) was isolated from the product formed by CoCl(2).6H(2)O and 1a. The nu(CO) values from the IR spectra of 6a and 7a suggest that 1a resembles a phosphonite in its bonding to Rh and Ir. Crystal structures of meso-2a, meso-2b, rac-6a and 9 are reported and in each case a small intracage C-P-C angle of ca. 94 degrees is observed; this may partly explain the bonding characteristics of ligands 1a and 1b. The cone angles for 1a and 1b are similar and large (ca. 200 degrees). Rhodium complexes of ligands 1a and 1b are hydroformylation catalysts with similarly high activity to catalysts derived from phosphites. The catalysts derived from 1a and 1b gave unusually low linear selectivity in the hydroformylation of hexenes. This feature has been further exploited in quaternary-selective hydroformylations of unsaturated esters; catalysts derived from 1a give better yields and regioselectivities than any previously reported catalyst.

[1]  G. Whiteker,et al.  Parallel ligand screening on olefin mixtures in asymmetric hydroformylation reactions. , 2004, Organic letters.

[2]  M. Clarke.  Rhodium catalysed hydroformylation of unsaturated esters , 2004 .

[3]  A. Spek,et al.  Rhodium Complexes of Sterically Demanding Diphosphonites: Coordination Chemistry and Catalysis. , 2004 .

[4]  B. Breit,et al.  Directed regio- and stereoselective hydroformylation of mono- and 1,3-disubstituted allylic alcohols: a catalytic approach to the anti-aldol-retron. , 2004, Chemical communications.

[5]  B. Breit,et al.  Phosphabarrelene-rhodium complexes as highly active catalysts for isomerization free hydroformylation of internal alkenes. , 2004, Chemical communications.

[6]  J. G. Vries,et al.  Rhodium-Catalysed Asymmetric Hydroformylation of Unsaturated Nitriles , 2003 .

[7]  A. Robertson,et al.  Novel class of tertiary phosphine ligands based on a phospha-adamantane framework and use in the Suzuki cross-coupling reactions of aryl halides under mild conditions. , 2003, Organic letters.

[8]  A. Orpen,et al.  Synthesis and transition metal chemistry of 'phosphomide' ligands: a comparison of the reactivity and electronic properties of diphenyl-P-perfluoro-octanoyl-phosphine, P-acetyl-diphenylphosphine and P-anisoyl-diphenylphosphine. X-ray crystal structure of [RhCp*(Ph2PC(O)CH3)Cl2] , 2003 .

[9]  E. Drent,et al.  Methoxycarbonylation versus Hydroacylation of Ethene; Dramatic Influence of the Ligand in Cationic Palladium Catalysis , 2002 .

[10]  Gemma L. Holliday,et al.  Highly electron rich alkyl- and dialkyl-N-pyrrolidinyl phosphines: an evaluation of their electronic and structural properties , 2002 .

[11]  M. Beller,et al.  Synthesis of Pyrrolyl-, Indolyl-, and Carbazolylphosphanes and Their Catalytic Application as Ligands in the Hydroformylation of 2-Pentene , 2001 .

[12]  E. Drent,et al.  Tandem isomerisation–carbonylation catalysis: highly active palladium(II) catalysts for the selective methoxycarbonylation of internal alkenes to linear esters , 2001 .

[13]  B. Breit,et al.  Phosphabenzenes as monodentate pi-acceptor ligands for rhodium-catalyzed hydroformylation. , 2001, Chemistry.

[14]  B. Breit,et al.  Recent Advances on Chemo-, Regio- and Stereoselective Hydroformylation , 2001 .

[15]  D. Stephan,et al.  Titanium Complexes of Sterically Demanding Cage-Phosphinimide Ligands , 2000 .

[16]  D. Selent,et al.  Novel Oxyfunctionalized Phosphonite Ligands for the Hydroformylation of Isomeric n-Olefins. , 2000, Angewandte Chemie.

[17]  A. Orpen,et al.  Bis(phospha-adamantyl)alkanes: a new class of very bulky diphosphines , 1999 .

[18]  G. Bekiaris,et al.  Phosphonous acid dichlorides and tricyclic phosphoranes from hexafluoro‐ and trifluoropentane‐2,4‐dione , 1998 .

[19]  G. Röschenthaler,et al.  Diastereoselective Synthesis and Molecular Structure of a Bicyclic and a Cage Phosphane , 1997 .

[20]  T. Nanno,et al.  Asymmetric hydroformylation catalyzed by an Rh(I)-(R, S)-BINAPHOS complex: substituent effects in olefins on the regioselectivity , 1997 .

[21]  A. Trzeciak,et al.  NOVEL RHODIUM COMPLEXES WITH N-PYRROLYLPHOSPHINES : ATTRACTIVE PRECURSORS OF HYDROFORMYLATION CATALYSTS , 1997 .

[22]  R. Grubbs,et al.  Safe and Convenient Procedure for Solvent Purification , 1996 .

[23]  B. Breit.  Highly regioselective hydroformylation under mild conditions with new classes of π-acceptor ligands , 1996 .

[24]  J. L. Petersen,et al.  N-Pyrrolyl Phosphines: An Unexploited Class of Phosphine Ligands with Exceptional .pi.-Acceptor Character , 1995 .

[25]  P. V. Leeuwen,et al.  Hydroformylation with a rhodium/bulky phosphite modified catalyst. A comparison of the catlyst behaviour for oct-1-ene, cyclohexene and styrene , 1995 .

[26]  G. Challa,et al.  A mechanistic study of rhodium tri(o-t-butylphenyl)phosphite complexes as hydroformylation catalysts , 1991 .

[27]  A. Orpen,et al.  Structural systematics. Part 3. Geometry deformations in triphenylphosphine fragments: a test of bonding theories in phosphine complexes , 1991 .

[28]  P. V. Leeuwen,et al.  Hydroformylation of oct-1-ene with extremely high rates using rhodium catalysts containing bulky phosphites , 1991 .

[29]  P. V. Leeuwen,et al.  Hydroformylation of less reactive olefins with modified rhodium catalysts , 1983 .

[30]  P. C. Kvande,et al.  Stereochemistry of 5-Co-ordinated Compounds. III. Some New Phosphine Complexes of Divalent Nickel and Cobalt. , 1963 .

[31]  S. A. Buckler,et al.  A Novel Phosphorus Heterocyclic System from the Reactions of Phosphine and Primary Phosphines with 2,4-Pentanedione , 1961 .