Direct synthesis of benzofuro[2,3-b]pyrroles through a radical addition/[3,3]-sigmatropic rearrangement/cyclization/lactamization cascade.

A straightforward synthetic method for the construction of benzofuro[2,3-b]pyrrol-2-ones by a novel domino reaction through a radical addition/[3,3]-sigmatropic rearrangement/cyclization/lactamization cascade has been developed. The domino reaction of O-phenyl-conjugated oxime ether with an alkyl radical allows the construction of two heterocycles with three stereogenic centers as a result of the formation of two C-C bonds, a C-O bond, and a C-N bond in a single operation, leading to pyrrolidine-fused dihydrobenzofurans, which are not easily accessible by existing synthetic methods. Furthermore, asymmetric synthesis of benzofuro[2,3-b]pyrrol-2-one derivatives through a diastereoselective radical addition reaction to a chiral oxime ether was also developed.