A five-bond-forming cascade reaction for synthesizing pyrazoline derivatives is described. The transformation involves N-(arylsulfonyl) acrylamides and in situ generated Huisgen zwitterions from azodicarboxylates and triphenylphosphine under mild, base-free conditions. A conjugate addition-Smiles rearrangement-cyclization sequence affords diverse pyrazolines in moderate to excellent yields. This work represents the first incorporation of Huisgen zwitterions into a Truce-Smiles cascade, enabling unprecedented five-bond construction in one step with demonstrated scalability and structural diversification.
Gao et al. (Mon,) studied this question.