Platinum derivatives optically active

A review9 with more than 37 references includes an examination of symmetry groups and chirality conditions for C60 and C70 bonded to one or two metals in rf and/or rf fashion. Palladium and platinum rf complexes of C6o and C70 are described (novel synthesis, NMR spectra, electrochemistry) as well as first optically active organometallic fullerene derivatives. 

In comparison with the platinum catalysts, rhodium catalysts are much more reactive to effect addition of bis(catecholato)diboron even to non-strained internal alkenes under mild reaction conditions (Equation (5)).53-55 This higher reactivity prompted trials on the asymmetric diboration of alkenes. Diastereoselective addition of optically active diboron derived from (li ,2i )-diphenylethanediol for />-methoxystyrene gives 60% de (Equation (6)).50 Furthermore, enantioselective diboration of alkenes with bis(catecolato)diboron has been achieved by using Rh(nbd)(acac)/(A)-QUINAP catalyst (Equation (7)).55,56 The reaction of internal (A)-alkenes with / //-butylethylene derivatives gives high enantioselectivities (up to 98% ee), whereas lower ee s are obtained in the reaction of internal (Z)-alkenes, styrene, and a-methylstyrene. 

Attempted reaction of 1,3-pentadiene with the optically active diboron derived from dialkyl tartrate in the presence of a phosphine-free platinum catalyst gave poor diastereoselectivity (20% de).63 Better selectivity has been attained with a modified platinum catalyst bearing a PCy3 ligand (Scheme 6).64 The reaction of allylborane thus obtained with an aldehyde followed by oxidation with basic hydrogen peroxide affords the corresponding diol derivative with moderate ee. 

An optically active derivative of palladium has been prepared by combining potassium chloropalladite with 1-propylenediamine. This salt has a rotation [a]o-f-79-25°, [M]d+258-1°. It is analogous to the corresponding platinum compound, but the rotation is much greater, thus showing the influence of the central metallic atom in increasing or diminishing the rotation.2... 

It is insoluble in water, microcrystallinc, and lilac in colour.1 Many of these derivatives of platinum containing organic bases have been obtained in optically active forms. Those containing 1-propylene-diamine will serve as examples. These are easily prepared, and as they are remarkably stable are easily examined for optical properties. The compounds are prepared by the interaction of cis-dichloro-l-propylenc-diamino-platinum, [Pt pnCl2], with the calculated quantity of the corresponding base, 1-propylcnediamine, ammonia, ethylenediamine, or trimethylenediamine. The liquid obtained is evaporated on a water-bath and precipitated with alcohol. The di-derivative of 1-propylene-diamine, [Pt pns]Cla, has rotation [a]o+46-37°, [M]r>+192-0°. 

Alkenes which have no symmetry planes perpendicular to the plane of the double bond such as Pmr-butene-2 or propene can coordinate to platinum in two enantiomorphous ways (77) and (78). If an optically active ligand is also bound to platinum(H), then two diastereoisomers are found which can be separated by fractional crystallization657,658 or by HPLC.659 Both cis and trans isomers of complexes PtCl(N—0)(alkene) have beenprepared, where N—O is an anion derived from an amino add (equations 235a and 235b).660-664 Epimerization cannot occur by simple rotation of the alkene about its bond axis, but only by a mechanism involving cleavage of the platinum(II)-alkene bond. 

Chiral olefins were reacted with optically platinum complexes, and the diastereomeric derivatives formed were separated by LC (229) thiols may be derivatized with optically active acetals for chromatographic resolution (230). The chromatographic separation of enantiomeric sugars, a rather specialized field, has been reviewed (231). 

Le Bel s resolution of a quaternary ammonium compound l abcdX. was doubtful, but Pope, S. J. Peachey, and A. W. Harvey resolved a quaternary nitrogen compound by means of camphorsulphonic acid. S. Smiles and Pope and Peachey prepared optically active sulphur compounds. Pope and Neville a selenium compound, and Pope and Peachey tin compounds. A very simple compound, CHCl SOgH), was resolved by Pope and Read. Pope and C. S. Gibson prepared alkyl derivatives of gold, and Pope and Peachey of platinum. 

Nickel and Platinum.—Cycloaddition reactions of various alkynes with CpgNi have afforded new derivatives of the known structural class CpNi(optically-active forms. The er-methyl complexes CpNi[P(OR)3]Me have been obtained from reactions of CpNi[P(OR)3]Cl with MeLi. Several new platinum complexes of the type CpPt(R)2X (R = alkyl X = alkyl or acyl) have been synthesized. ... 

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