A highly efficient, green, and multicomponent reaction for 32 spirooxindole derivatives via the formation of cascade C–N, C–O, and C–S bonds using starch-capped zinc oxide nanocomposite as an effective heterogeneous catalyst with the synergistic application of ultrasound and on-water synthesis has been developed.

A highly efficient, green, and multicomponent reaction method has been developed for the diversity-oriented synthesis of 32 spirooxindole derivatives via the formation of cascade C–N, C–O, and C–S bonds. The synthesis involved starch-capped zinc oxide nanocomposite as an effective heterogeneous catalyst with the synergistic application of ultrasound and on-water synthesis. By employing this approach, all desired products were successfully obtained with high yields and comparatively short reaction times. Furthermore, the catalyst employed in the process exhibited excellent recyclability, allowing for its recovery and reuse for up to eight consecutive runs without any loss of catalytic activity. The greenness of the protocol was evaluated by various green metrics such as E-factor and eco-score, and the result showed the acceptability of the present method in organic synthesis.