On the Mechanism of Carbohydroxypalladation of Enynes. Additional Insights on the Cyclization of Enynes with Electrophilic Metal Complexes

• Published in: European journal of organic chemistry Vol. 2003; no. 4; pp. 706 - 713
• Main Authors: Nevado, Cristina, Charruault, Lise, Michelet, Véronique, Nieto-Oberhuber, Cristina, Muñoz, M. Paz, Méndez, María, Rager, Marie-Noëlle, Genêt, Jean-Pierre, Echavarren, Antonio M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.02.2003; WILEY‐VCH Verlag; Wiley
• Subjects: Carbocycles; Chemistry; Chemistry, Organic; Cyclization; Enynes; Palladium; Physical Sciences; Platinum; Science & Technology; ROUTE; carbocycles; SKELETAL REORGANIZATION; enynes; ALKYNES; cyclization; HYDRATION; PD-CATALYZED CYCLOISOMERIZATION; platinum; CROSS-COUPLING REACTIONS; palladium; INTRAMOLECULAR REACTION; EFFICIENT; METATHESIS; PICROTOXANE SESQUITERPENES
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200390110

Different mechanisms have been proposed for the cyclization of enynes catalyzed by electrophilic metal halides or complexes. We present evidence to indicate that the previously reported “carbohydroxypalladation” and the “hydroxycyclization catalyzed by PtII” are closely related reactions. Thus, palladium complexes formed in situ from PdCl2 and trisulfonated phosphane TPPTS or cyclic phosphite P(OCH2)3CEt as the ligands catalyze the methoxy‐ or hydroxycyclization of enynes with selectivities similar to those observed with PtII complexes. Deuteration studies indicate that activation of the alkyne by PdII promotes an anti‐addition of the alkene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)