Nickel(0)-Catalyzed Enantioselective Annulations of Alkynes and Arylenoates Enabled by a Chiral NHC Ligand: Efficient Access to Cyclopentenones

• Published in: Angewandte Chemie Vol. 126; no. 48; pp. 13445 - 13449
• Main Authors: Ahlin, Joachim S. E., Donets, Pavel A., Cramer, Nicolai
• Format: Journal Article
• Language: English; German
• Published: Weinheim WILEY-VCH Verlag 24-11-2014; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Alkynes; Anellierungen; Asymmetrische Katalyse; Asymmetry; Carbene; Carbenes; Chemical reactions; Chemistry; Cyclopentenone; Esters; Ligands; Nickel; Organic chemistry; Synthesis
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201408364

Cyclopentenones are versatile structural motifs of natural products as well as reactive synthetic intermediates. The nickel‐catalyzed reductive [3+2] cycloaddition of α,β‐unsaturated aromatic esters and alkynes constitutes an efficient method for their synthesis. Here, nickel(0) catalysts comprising a chiral bulky C1‐symmetric N‐heterocyclic carbene ligand were shown to enable an efficient asymmetric synthesis of cyclopentenones from mesityl enoates and internal alkynes under mild conditions. The bulky NHC ligand provided the cyclopentenone products in very high enantioselectivity and led to a regioselective incorporation of unsymmetrically substituted alkynes.
Cyclisierung: Nickel(0)‐Katalysatoren mit einem chiralen, sperrigen C1‐symmetrischen N‐heterocyclischen Carben als Liganden ermöglichten die Titelreaktion von Enoaten und Alkinen zu substituierten Cyclopentenonen unter milden Bedingungen. Das System liefert die Produkte mit hoher Enantioselektivität und führt zum regioselektiven Einbau unsymmetrisch substituierter Alkine.