ABSTRACT A one‐pot sequential four‐component reaction for the diastereoselective synthesis of 3‐phosphonyloxy‐3‐chromenyl‐disubstituted oxindoles is described. The reaction proceeds via the base‐mediated addition of diethylphosphite to isatins followed by a 1,2‐phospha‐Brook rearrangement, generating α‐phosphonyloxy enolates. These enolates are subsequently trapped by 2‐iminochromene intermediates, derived in situ from salicylaldehydes and malononitrile, to afford phosphate‐incorporated 3,3‐disubstituted oxindole derivatives in high yields and with good diastereoselectivity. This methodology offers significant advantages, including step economy, reduced waste, operational simplicity, and the use of aqueous ethanol as an environmentally and economically sustainable solvent.
Wu et al. (Thu,) studied this question.
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