A new class of bidentate phosphoramidite ligands, based on a spiroketal backbone, has been developed for the rhodium-catalyzed hydroformylation reactions. A range of short- and long-chain olefins, were found amenable to the protocol, affording high catalytic activity and excellent regioselectivity for the linear aldehydes. Under the optimized reaction conditions, a turnover number (TON) of up to 2.3×10⁴ and linear to branched ratio (l/b) of up to 174.4 were obtained in the Rh^I-catalyzed hydroformylation of terminal olefins. Remarkably, the catalysts were also found to be efficient in the isomerization–hydroformylation of some internal olefins, to regioselectively afford the linear aldehydes with TON values of up to 2.0×10⁴ and l/b ratios in the range of 23.4–30.6. X-ray crystallographic analysis revealed the cis coordination of the ligand in the precatalyst [Rh(3 d)(acac)], whereas NMR and IR studies on the catalytically active hydride complex [HRh(CO)₂(3 d)] suggested an eq–eq coordination of the ligand in the species.

Iron–palladium is a superior bimetallic catalyst in the presence of acetylacetone (Acac) with remarkable synergistic effect for the Michael-type Friedel–Crafts reactions of indoles with chalcones. This catalytic system has the advantages of mild reaction conditions, smaller amount of metal salts, high yields of the desired products and operational simplicity, which make it a useful and promising process for the synthesis of indole derivatives. Copyright © 2009 John Wiley & Sons, Ltd.

The double carbonylation of iodobenzene and diethylamine proceeds smoothly in the presence of Pd/C and carbon monoxide to afford the corresponding α-keto amide in good yields with excellent selectivity. In addition, other aryl iodides and secondary amines also react under similar conditions to form α-keto amides in good yields.

Reaction of acetylferrocene thiosemicarbazone [L] with Ru₃(CO)₁₂ was investigated. Two new complexes, Ru₃(CO)₉[L-H] (1) and Ru₂(CO)₄[L]₂ (2) were isolated. They were characterized by IR, ¹H NMR, and ¹³C NMR spectroscopic analysis. The crystal structures of 1 and 2 were also determined. In trinuclear cluster 1, the acetylferrocene thiosemicarbazone ligand was deprotonated and acted as an N,S-chelating ligand as well as a sulfur bridge. Dinuclear compound 2 is the first bis(cycloruthenated acetylferrocene thiosemicarbazone) carbonyl derivative. This complex contains two ruthenium atoms in a dinuclear structure with a C_ferrocene, N, S₂, and (CO)₂ coordination sphere for each ruthenium atom, as both L ligands act as a C_ferrocene, N, S₂ chelate, and sulfur bridge. The behavior of 1 and 2 under electrospray ionization mass spectrometry (ESI-MS) was studied and the key intermediate Ru(CO)₂[L-H] (3) in the formation of 2 was directly detected in the reaction solution.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A new class of C₂-symmetric chiral bidentate phosphonite ligands has been synthesized in moderate to good yields from readily available starting materials. Application of these air-stable chiral phosphonites in the Rh^I-catalyzed asymmetric hydroformylation of styrene derivatives, vinyl acetate, and allyl cyanide afforded the corresponding chiral aldehydes with high regio- and enantioselectivities under mild reaction conditions. The modular nature of the ligands allows fine-tuning of the selectivities through judicious modifications of the substituents on the ligand backbone. X-ray structural analysis of the catalyst precursor suggested that the steric hindrance caused by the protruding remote substituents of the ligands into the vicinity of the metal center might be an important factor for the enantio-control of the reaction, whereas the sense of asymmetric induction can be rationalized on the basis of a trigonal-bipyramidal transition state diagram.