Synthesis of highly substituted indole alkaloid species via [4+1] cyclization of nucleophilic carbenes and indole isocyanates
Thermally induced [4+1] cyclization between indole isocyanates and dimethoxycarbene or bis(propylthio)carbene has been achieved with good chemical efficiency. The methodology provides rapid access to fused pyrroloindole substructures commonly found in a variety of indole alkaloid natural products.