Elisabeth Hauptman

Metal-Catalyzed Selective Deoxygenation of Diols to Alcohols

The internal OH group of 1,2-propanediol is selectively removed in the deoxygenation catalyzed by [{Cp*Ru(CO)2 }2 (μ-H)]+ OTf- (1, Cp*=C3 Me5 , OTf=trifluoromethanesulfonate; see scheme). This reaction provides a model for deoxygenation of polyols derived from carbohydrates, for use in alternative, biomass-based feedstock applications. An ionic mechanism is proposed that involves the dihydrogen complex [Cp*Ru(CO)2 (η2 -H2 )]+ .

α-Nitrogen activating effect in the room temperature copper-promoted N-arylation of heteroarylcarboxamides with phenyl siloxane or p-toluylboronic acid

Abstract Heteroarylcarboxamides containing α-nitrogens undergo copper-promoted N -phenylation with hypervalent phenyl trimethylsiloxane at room temperature, in the absence of base and in air . Arylboronic acid can substitute for phenyl trimethylsiloxane as the organometalloid. The α-heteroatom chelating effect is in the decreasing order of N>O, S. This discovery opens up the possibility of using other α-nitrogen functional groups to direct the N -arylation of peptides and simple amides under conditions as mild as that of amide bond formation.

Synthesis of ruthenium carbonyl complexes with phosphine or substituted Cp ligands, and their activity in the catalytic deoxygenation of 1,2-propanediol

A ruthenium hydride with a bulky tetra-substituted Cp ligand, (Cp(i)(Pr(4)))Ru(CO)(2)H (Cp(i)(Pr(4)) = C(5)(i-C(3)H(7))(4)H) was prepared from the reaction of Ru(3)(CO)(12) with 1,2,3,4-tetraisopropylcyclopentadiene. The molecular structure of (Cp(i)(Pr(4)))Ru(CO)(2)H was determined by X-ray crystallography. The ruthenium hydride complex (C(5)Bz(5))Ru(CO)(2)H (Bz = CH(2)Ph) was similarly prepared. The Ru-Ru bonded dimer, [(1,2,3-trimethylindenyl)Ru(CO)(2)](2), was produced from the reaction of 1,2,3-trimethylindene with Ru(3)(CO)(12), and protonation of this dimer with HOTf gives {[(1,2,3-trimethylindenyl)Ru(CO)(2)](2)-(mu-H)}(+)OTf (-). A series of ruthenium hydride complexes CpRu(CO)(L)H [L = P(OPh)(3), PCy(3), PMe(3), P(p-C(6)H(4)F)(3)] were prepared by reaction of Cp(CO)(2)RuH with added L. Protonation of (Cp(i)(Pr(4)))Ru(CO)(2)H, Cp*Ru(CO)(2)H, or CpRu(CO)[P-(OPh)(3)]H by HOTf at -80 degrees C led to equilibria with the cationic dihydrogen complexes, but H(2) was released at higher temperatures. Protonation of CpRu[P(OPh)(3)](2)H with HOTf gave an observable dihydrogen complex, {CpRu[P-(OPh)(3)](2)(eta(2)-H(2))}(+)OTf (-) that was converted at -20 degrees C to the dihydride complex {CpRu[P(OPh)(3)](2)(H)(2)}(+)OTf (-). These Ru complexes serve as catalyst precursors for the catalytic deoxygenation of 1,2-propanediol to give n-propanol. The catalytic reactions were carried out in sulfolane solvent with added HOTf under H(2) (750 psi) at 110 degrees C.

Steric and electronic effects of R in (2-(4-R-C6H4)indenyl)2ZrCl2 catalysts on the synthesis of elastomeric polypropylene

Metallocene catalysts derived from bis(2-arylindenyl)zirconium dichloride catalysts yield elastomeric stereoblock polypropylene. A study of the steric and electronic effects of varying the 4-substituent of bis(2-(4-R-C6H4)indenyl)zirconium dichloride [(1 RH, 2 RMe, 3 REt, 4 RnBu, 5 RtBu, 6 RSiMe3, 7 RCF3, 8 RCl)] on propylene polymerization at 25, 50, 75 psig and bulk propylene revealed that the polymerization behavior of these catalysts is not strongly influenced by the nature of the substituent in the 4-position of the 2-aryl substituent. Examinations of the microstructure of the elastomeric polypropylenes produced showed that for catalysts 2–8 the isotacticities varied over a small range and were similar to those produced by catalyst 1 (20%≤[mmmm]≤44%). The catalyst productivities and molecular weights also showed the same trend. Complex 3 was crystallographically characterized and was found to crystallize in exclusively the meso conformation.

Solvent-free ketone hydrogenations catalyzed by molybdenum complexesElectronic supplementary information (ESI) available: additional spectroscopic data and description of the synthetic procedures. See http://www.rsc.org/suppdata/cc/b4/b401760a/

Et2C=O is hydrogenated under solvent-free conditions using a catalyst prepared by hydride abstraction from HMo(CO)2[eta5:eta1-C5H4(CH2)(2)PCy2]; the catalyst functions at low catalyst loadings (< 0.4 mol%).