Asymmetric synthesis of spirofuro[2,3-b]azepine-5,3′-indoline derivatives via cycloisomerization/[4+3] annulation process under Au/N-heterocyclic carbene relay catalysis

A variety of enantioenriched spirofuro[2,3-b]azepine-5,3 & PRIME;-indoline derivatives (dr > 20 : 1, up to 96% ee) were facilely synthesized through cycloisomerization/asymmetric formal [4 + 3] cycloaddition reactions of enyne-amides with isatin-derived enals under gold(i)/chiral N-heterocyclic carbene (NHC) relay catalysis. The method is practical and useful because of the convenient one-step procedure, high stereoselectivity, and good functional-group tolerance.

Automated summary

A practical and useful method for the synthesis of enantioenriched spirofuro[2,3-b]azepine-5,3 & PRIME;-indoline derivatives was developed. This method involves cycloisomerization/asymmetric formal [4 + 3] cycloaddition reactions using enyne-amides and isatin-derived enals under gold(i)/chiral N-heterocyclic carbene (NHC) relay catalysis, resulting in high stereoselectivity (dr > 20 : 1, up to 96% ee) and good functional-group tolerance.