Ag(i)-catalyzed tandem [6+3] annulation/isomerization of isocyanoacetates with fulvenes: an expedient approach to synthesize fused dihydropyridines

Abstract

An unprecedented Ag(i)-catalyzed tandem [6+3] cycloaddition/isomerization of isocyanoacetates with fulvenes has been developed, affording the fused dihydropyridine derivatives in good yields with exclusive regioselectivities.

Metal‐Catalyzed C−H Bond Activation of 5‐Membered Carbocyclic Rings: A Powerful Access to Azulene, Acenaphthylene and Fulvene Derivatives

“…Wang et al. described in 2015 the Ag I ‐catalyzed tandem [6+3] cycloaddition/isomerization of isocyanoacetates with fulvenes affording dihydropyridines (Scheme ) . Using 3 mol % AgOAc/PPh 3 as the catalyst and Et 3 N as the base at room temperature in dichloromethane, the tandem cycloaddition/isomerization products were obtained in high yields.…”

“…Wang et al described in 2015 the Ag I -catalyzed tandem[ 6 + +3] cycloaddition/isomerization of isocyanoacetates with fulvenes affording dihydropyridines (Scheme32). [36] Using 3mol % AgOAc/PPh 3 as the catalysta nd Et 3 Na st he base at room temperaturei nd ichloromethane, the tandemc ycloaddition/isomerization products were obtained in high yields. The use of other silver salts, such as AgNO 3 ,A g 2 CO 3 and AgClO 4 ,a lso afforded the cycloaddition/isomerization products, but in slightly lower yields.…”

Silver‐Catalyzed Chemoselective [4+2] Annulation of Two Isocyanides: A General Route to Pyridone‐Fused Carbo‐ and Heterocycles

“…[1][2][3][4][5][6][7][8] These reactions mainly involve the participation of activated methylene isocyanides (as at hree-atom component) in [3+ +2], [3] [3+ +3], [4] and [3+ +6] annulations [5] and of isocyanides (as ao ne-atom component) in [1+ +4], [2,6] [1+ +5], [7] and [1+ +2+ +2] annulations. [1][2][3][4][5][6][7][8] These reactions mainly involve the participation of activated methylene isocyanides (as at hree-atom component) in [3+ +2], [3] [3+ +3], [4] and [3+ +6] annulations [5] and of isocyanides (as ao ne-atom component) in [1+ +4], [2,6] [1+ +5], [7] and [1+ +2+ +2] annulations.…”

“…

Asilver-catalyzed chemoselective [4+ +2] annulation of aryl and heteroaryl isocyanides with a-substituted isocyanoacetamides was developed for the facile and efficient synthesis of 2-aminoquinolones,n aphthyridines,a nd phenanthrolines.Amechanism for this multistep domino reaction is proposed on the basis of a 13 C-labeling experiment, according to whichanunprecedented chemoselective heterodimerization of two different isocyanides generates an a-amidoketenimine intermediate,whichundergoes 1,3-amino migration to form an a-imidoylketene,followed by 6 p electrocyclization.During the past decade,isocyanide-based cycloaddition has been well developed and shown to be one of the most powerful strategies for the synthesis of diverse classes of heterocycles. [1][2][3][4][5][6][7][8] These reactions mainly involve the participation of activated methylene isocyanides (as at hree-atom component) in [3+ +2], [3] [3+ +3], [4] and [3+ +6] annulations [5] and of isocyanides (as ao ne-atom component) in [1+ +4], [2,6] [1+ +5], [7] and [1+ +2+ +2] annulations. [8] Among these transformations,t he [3+ +2] cycloaddition of activated methylene isocyanides with aryl isocyanides has emerged as an efficient protocol for the catalytic synthesis of imidazoles [Scheme 1, Eq.

…”

“…During the past decade,isocyanide-based cycloaddition has been well developed and shown to be one of the most powerful strategies for the synthesis of diverse classes of heterocycles. [1][2][3][4][5][6][7][8] These reactions mainly involve the participation of activated methylene isocyanides (as at hree-atom component) in [3+ +2], [3] [3+ +3], [4] and [3+ +6] annulations [5] and of isocyanides (as ao ne-atom component) in [1+ +4], [2,6] [1+ +5], [7] and [1+ +2+ +2] annulations. [8] Among these transformations,t he [3+ +2] cycloaddition of activated methylene isocyanides with aryl isocyanides has emerged as an efficient protocol for the catalytic synthesis of imidazoles [Scheme 1, Eq.…”