Synthesis of 1,4‐Cyclohexadiene Carboxylates through a Formal [2+4]‐Cycloaddition of Propiolates under Cobalt Catalysis

• Published in: Helvetica chimica acta Vol. 103; no. 12
• Main Authors: Charpentier, Julie, Voirol, Francis, Flachsmann, Felix, Tanner, Silvia, Aeberli, Natalie, Brunner, Gerhard, Goeke, Andreas
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 01.12.2020; Wiley Subscription Services, Inc
• Subjects: alkynes; Aromatic compounds; Carboxylates; Catalysis; Catalysts; Chemistry; Chemistry, Multidisciplinary; Cobalt; Cycloaddition; cyclohexadiene; Dienes; Flowers; fragrance chemistry; Odor; Odors; Physical Sciences; Science & Technology; cyclohexadiene; fragrance chemistry; cycloaddition; DIELS-ALDER REACTIONS; 1,3-DIENES; COBALT(I)-CATALYZED 6+2 CYCLOADDITIONS; alkynes; COMPLEXES; catalysis; cobalt; BIRCH REDUCTION
• ISSN: 0018-019X; 1522-2675
• DOI: 10.1002/hlca.202000175

A low‐valent cobalt(I) complex, formed from the reduction of CoBr2(dppe) with zinc, acts as catalyst for the efficient [2+4] cycloaddition of β‐alkyl, cycloalkyl and aryl substituted propiolates to dienes. This transformation yields synthetically relevant 1,4‐cyclohexadiene carboxylates in good to excellent yields. Furthermore, the target compounds are novel lead structures for the discovery of fragrance ingredients from the fruity, floral and spicy odor family.