Synlett 2005(4): 667-669  
DOI: 10.1055/s-2005-863718
LETTER
© Georg Thieme Verlag Stuttgart · New York

Rhodium-Catalyzed Addition-Cyclization Reactions of 5-Yn-1-ones with Arylboronic Acids

Tomoya Miura, Masahiko Shimada, Masahiro Murakami*
Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan
Fax: +81(75)3832748; e-Mail: murakami@sbchem.kyoto-u.ac.jp;
Further Information

Publication History

Received 10 December 2004
Publication Date:
22 February 2005 (online)

Abstract

5-Yn-1-ones react with arylboronic acids in the presence of a catalytic amount of rhodium(I) complex having a diolefin ligand to afford 2-alkylidenecyclopentanols through the regioselective addition of an arylrhodium(I) species across the carbon-carbon triple bond, followed by intramolecular nucleophilic addition of the resulting vinylrhodium(I) species to the carbonyl group.

7

General Procedure for Cyclization of 5-Yn-1-ones.
To an oven-dried, N2-purged flask was added [Rh(OH)(cod)]2 (2.28 mg, 0.5 µmol, 0.05 equiv of Rh), arylboronic acid (1.0 mmol, 5.0 equiv), 1,4-dioxane (1 mL), and H2O (20 µL). A solution of substrate (0.2 mmol, 1.0 equiv) in 1,4-dioxane (1.0 mL) was added to the reaction mixture at r.t. After complete consumption of substrate, H2O was added. The aqueous layer was extracted with EtOAc three times. The combined extracts were washed with brine and dried over MgSO4. The solvent was removed under reduced pressure and the residue was purified by preparative thin-layer chromatography (hexane-EtOAc) to give the product.

8

When rhodium(I) complex generated in situ from [Rh(OH)(cod)]2 and (R)-BINAP was used, the ee was lower (55% ee) than that of the isolated [Rh(OH)(binap)]2.