Sunday, May 6, 2007

Rhodium-Catalyzed Asymmetric Synthesis of 3,3-Disubstituted 1-Indanones


Ryo Shintani, Keishi Takatsu, Tamio Hayashi

Angewandte Chemie International Edition; 2006, 46, 3537-3737
DOI: 10.1002/anie.200700226

Summary: Chiral indanones that are difficult to obtain by other synthetic methods can be prepared via an enantioselective addition of aryl boronates to aryl alkynyl ketones. The resulting substituted indanones arrive from a tandem Rh-catalyzed C-H functionalization-cyclization sequence. This reaction utilizes a rhodium catalyst system with the asymmetric induction originating from a chiral bisphosphine ligand.

Saturday, May 5, 2007

Palladium-Catalyzed Benzene Arylation: Incorporation of Catalytic Pivalic Acid as a Proton Shuttle and a Key Element in Catalyst Design


Marc Lafrance and Keith Fagnou
J. Am. Chem. Soc., 2006, 128, 16496 -16497
Summary: C-H activation processes represent an important area of synthetic exploration since the starting materials required are less functionalized and potentially less expensive. A Pd-pivalic acid co-catalyst system has been utilized in the direct arylation of benzene and aryl bromides. Experimental and computational studies indicate that the pivalate anion is a key component in the palladation/C-H bond breaking event. Additionally, aryl chorides and iodides were found to be poor substrates.

8 examples: 55-85%