Adrian W. Parkins

The catalytic hydration of nitriles to amides using a homogeneous platinum phosphinito catalyst

Abstract New homogeneous catalysts for the hydration of nitriles to amides are described. The catalyst precursors are coordination compounds of Pt(II) with secondary phosphine oxides. They contain a hydrogen bridged mono-anionic didentate phosphinito group, together with a third phosphine oxide ligand and a monodentate anionic ligand, either hydride or chloride. Reacting the chloride with silver ion, or the hydride with water gives a cationic species which is the active catalyst. On coordination to the cation the nitrile becomes susceptible to nucleophilic attack. The hydrolysis gives the amide as the sole product, and there is no tendency towards further hydrolysis to the acid. The effects of substituents on phosphorus are investigated, and a reaction mechanism is suggested. The most active catalyst, [PtH(PMe2OH)(PMe2O)2H], 2a, is derived from dimethylphosphine oxide, and this precursor catalyses the hydration of acrylonitrile to acrylamide with a turnover number of 77,000, without addition to the CC double bond.

A NEW HOMOGENEOUS PLATINUM CONTAINING CATALYST FOR THE HYDROLYSIS OF NITRILES

Abstract [(Me2PO···h ···OPMe2)PtHiPMe2OH)] is an extremely active homogeneous catalyst for the hydration of nitriles to amides: a mechanism involving intramolecular attack by a phosphine oxide on a nitrile within the co-ordination sphere of the platinum atom is suggested.

The crystal structure of 1,1′-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyldicarbonyl)ruthenocene

Abstract The crystal and molecular structure of the ruthenocene-containing cryptand 1,1′-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyldicarbonyl)ruthenocene has been determined. The ruthenocene rings are separated by 3.62(1) A, rotated from eclipsed by ca. 2° and are almost parallel with dihedral angle 1.1(4)°. The carbonyl substituents are trans with substitution at the ruthenocene rings staggered by 73.7°.

SYNTHESIS OF O-PROTECTED MANDELAMTOE AND ITS ELABORATION TO 5-HYDROXY-l,5-DIPHENYLHYDANTOIN

inum-containing catalyst A for the hydration of nitriles to amides, and its application to the synthesis of atenolol.4 Since it was found that A does not catalyze the direct hydration of mandelonitrile 1 to mandelamide 4, we decided to investigate whether an 0-protected cyanohydrin could be converted to the amide (Scheme). Mandelonitrile 1 was converted to the mixed acetal 2s which was hydrated to 3 in 88% yield using A as catalyst; removal of the protecting group with dilute acid gave mandelamide 4. Since some difficulties were encountered when we tried to catalyze the reaction between 3 and phenyl isocyanate, the thermal reaction of 3 with phenyl isocyanate was performed in refluxing toluene and gave the substituted urea 5a, which was not isolated, and which on deprotection gave N-mandelyl-N-phenylurea 5b. The thermal reaction of amides with phenyl isocyanate was originally reported (without solvent) by Kiihn6 in 1884, and subsequently in toluene7 or xylene8 as solvent. may be achieved using borate ion catalysis? involving the formation of a

Di-μ-chlorobis[hydrogen bis(diphenylphosphinito)(1–)-P,P']dipalladium, [Pd2Cl2{(C6H5)2PO⋯H⋯OP(C6H5)2}2]

The title compound consists of dinuclear chlorobridged palladium units with two coordinated diphenylphosphinito groups per Pd atom, linked by a hydrogen bridge. The average O...O distance in the O...H...O bridges of the two independent molecules is 2.406 (4) A, which is comparable to values in similar phosphinato groups

Studies towards the catalytic anti-Markovnikov functionalisation of alkenes

In 1986 Jensen and Trogler reported that a biphasic system containing the mononuclear complex trans-[(Me3P)2PtHCl] and NaOH catalysed the anti-Markovnikov hydration of 1-hexene to 1-hexanol. The unusual method of preparation could also give rise to dinuclear complexes with bridging hydride ligands. We have tested some dinuclear complexes for catalytic activity and discovered that on heating these yield trinuclear complexes. Using the independently prepared trinuclear complex [(dppe)3Pt3H3]+, we found that it acted as a catalyst for the reaction between 1-octene and methanol to give 1-methoxyoctane, although the results were somewhat erratic. A cause of the erratic behaviour was found to be the presence of varying amounts of hydroperoxide impurities, which underwent a Hock rearrangement in acidic conditions.

Some reactions of 2,4-diphosphaplatinocycles and the crystal structures of

Abstract The structure of the ring insertion product 1b obtained from the reaction of [Pt(dppm)(CH2Cl2] (dppm = Ph2PCH2PPh2) with triphenylphosphine has been confirmed by X-ray crystallography of the hexafluorophosphate salt. The bis-chelate complex (IIIa) has been isolated from the reaction of [Pt(dppm)(CH2Cl2] (II) with diphenylphosphine in dichloromethane. Iodination of Ib leads to selective cleavage of the chloromethyl group, and subsequent iodide abstraction with silver ion gives a solvated cation (V). The structures of the hexafluorophosphate salts of the bis-chelate IIIb and of the solvated cation V have been determined by X-ray diffraction.

The orthopalladation of aniline via its 2-nitrophenylsulfenyl derivative

Abstract 2-Nitrophenylsulfenylanilide can be orthopalladated to give μ,μ-dichlorodipalladium-bis(2-nitrophenylsulfenylanilide), which on carbomethoxylation gives 2-nitrophenylsulfenylanthranilate.

The synthesis of N-heterocycles using ortho-metallated primary benzylamine complexes of palladium(II) and platinum(II)

The synthesis of the isoindolinimines (5) by the insertion of isocyanides into the metal–carbon bond of the ortho-palladated primary benzylamine complex (1a) is described; the novel oxidative addition and susbsequent reductive elimination of the ortho-metallated primary benzylamine–platinum complex (6) yields 3-oxo-1,2,3,4-tetrahydroisoquinoline (8).

The crystal structure of 5-(2-nitrophenylmethylene)-2-thioxothiazolidin-4-one-3-(α-benzyl)ethanoic acid: Preference for the Z-configuration

X-ray crystal structure analysis of the title compound shows that it has the Z-configuration at the exocyclic double bond. Steric hindrance within the molecule is responsible for a considerable deviation from planarity in some regions of the molecule. The relationship of this compound to the structural pattern shown by other thiazolidin-4-one derivatives is briefly discussed.