Gold(I)-Catalyzed Cyclizations of 1,6-Enynes: Alkoxycyclizations and exo/endo Skeletal Rearrangements

• Published in: Chemistry : a European journal Vol. 12; no. 6; pp. 1677 - 1693
• Main Authors: Nieto-Oberhuber, Cristina, Muñoz, M. Paz, López, Salomé, Jiménez-Núñez, Eloísa, Nevado, Cristina, Herrero-Gómez, Elena, Raducan, Mihai, Echavarren, Antonio M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 08.02.2006; WILEY‐VCH Verlag; Wiley
• Subjects: alkynes; Chemistry; Chemistry, Multidisciplinary; cyclization; gold; iron; Physical Sciences; rearrangement; Science & Technology; PAUSON-KHAND REACTION; PALLADIUM; ENE CYCLIZATIONS; MECHANISM; alkynes; PLATINUM; CATIONIC GOLD(I) COMPLEXES; cyclization; CATALYZED CYCLOISOMERIZATION REACTIONS; gold; ENYNE METATHESIS; iron; REORGANIZATION; CARBENE COMPLEXES; rearrangement
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200501088

Gold(I) complexes are the most active catalysts for alkoxy‐ or hydroxycyclization and for skeletal rearrangement reactions of 1,6‐enynes. Intramolecular alkoxycyclizations also proceed efficiently in the presence of gold(I) catalysts. The first examples of the skeletal rearrangement of enynes by the endocyclic cyclization pathway are also documented. Iron(III) is also able to catalyze exo and endo skeletal rearrangements of 1,6‐enynes, although the scope of this transformation is more limited. The gold(I)‐catalyzed endocyclic cyclization proceeds by a mechanism different from those followed in the presence of PdII, HgII, or RhI catalysts. Selective activation of alkyne functions of enynes to give products either of alkoxycyclization or of exo‐ and endo‐skeletal rearrangement can be achieved by using alkynophilic cationic gold(I) complexes (see scheme). Endocyclic cyclization catalyzed by gold(I) proceeds by a mechanism different from those followed in the presence of PdII, HgII, or RhI catalysts.