A Gold-Catalyzed Unique Cycloisomerization of 1,5-Enynes:  Efficient Formation of 1-Carboxycyclohexa-1,4-dienes and Carboxyarenes

Abstract

A novel Au-catalyzed migratory cycloisomerization strategy is advanced. Implementation of this strategy led to the development of a unique Au-catalyzed 1,5-enyne cycloisomerizatioin involving carboxy migration and Au-mediated C-C single bond formation. 1-Carboxycyclohexa-1,4-dienes and carboxyarenes can be prepared with good efficiency and with flexible substitution patterns.

PtI2-catalyzed cyclization of 3-acyloxy-1,5-enynes with the elimination of HOAc and a benzyl shift: synthesis of unsymmetrical m-terphenyls

“…Gaining insight into the m-terphenyl product, we observed that a new central benzene ring was constructed via the cyclization and consecutive aromatization of 1,5-enynes without the need for additional oxidation. 8 Notably, in the product 4, the original substituent (R 1 ) on the alkene terminal (C1 position) of 1,5-enynes and the substituent (R 2 ) on the alkyne terminal (C6 position) are located at the meta-position of the newly formed central cyclic ring (Scheme 1c). In other words, the possible migration of the alkyl group involved in this cyclization is completely different from the previous reports.…”

Nature of the Intermediates in Gold(I)‐Catalyzed Cyclizations of 1,5‐Enynes

“…[29] According to DFT calculation, this intramolecular cyclopropanation from 1,5-enynes proceeds by a concerted process similar to that found before for the Scheme 9. Comparison between the intramolecular arylation of 1,5-enynes (9) with that of 1,6-enynes (28).…”

“…In contrast to 1,6-enynes, which usually react by 6-exo-dig pathways with gold(I) catalysts, [1] 1,5-enynes 1 almost invariably undergo 5-endo-dig cyclizations through intermediates of type 2 to form derivatives 3, [1][2][3][4][5][6][7][8][9] since formation of intermediates with a bicycloA C H T U N G T R E N N U N G [3.1.0]hexane structure is more favorable than formation of the strained bicycloA C H T U N G T R E N N U N G [2.1.0]pentane system resulting from exo cyclization (Scheme 1). [10,11,12] Ligands play a major role in the control of the regio or site selectivity in gold-catalyzed reactions of 1,6-enynes.…”

Nickel‐Catalyzed Reductive Cyclization of Unactivated 1,6‐Enynes in the Presence of Organozinc Reagents

“…(3)]. Such unactivated enynes have historically been used in combination with catalytic systems based on Pd, [16][17][18][19] Au, [20] Ru, [21] and Rh. [19,[22][23][24] We and others have described highly enantioselective Rh-mediated cycloisomerization reactions of 1,6-enynes [Scheme 1, Eq.…”