Convergent Assembly\nof 1,4-Benzothiazide Spiroindolinones\nvia [4 + 2] Spiroannulation Under Open-Air Conditions

This\nreport discloses a transition-metal-free [4 + 2] spirocyclization\nof isatin-derived β-silylcarbinols and 2-aminobenzenethiols,\nproviding a facile approach to 1,4-benzothiazide spiroindolinones\nin decent yields. Control experiments indicate that 3-methylene oxindoles\nand disulfides are key intermediates in this tandem reaction. Moreover,\nthe resulting products can be facilely converted into pharmaceutically\nsignificant sulfone and sulfoxide scaffolds, which further demonstrates\nthe potential utility of this protocol.