Alternative Approach to Access 5-Hydroxy-1H-pyrrol-2-(5H)-ones from Base-Induced Tandem Intramolecular Cyclization of Sulfur Ylide with Ketones and 1,3-Hydroxy Rearrangement.

An easily adaptable protocol for the preparation of 5-hydroxy-1H-pyrrol-2(5H)-ones from readily available starting materials has been reported. The reaction of sulfur ylides with carbonyl compounds is a common approach to synthesizing epoxides. Alternatively, we have developed a method with mild reaction conditions wherein sulfur ylide underwent an intramolecular cyclization with a ketonic carbonyl group in a highly efficient way and was followed by 1,3-hydroxy rearrangement to produce 5-hydroxy-1H-pyrrol-2(5H)-ones in excellent yields. The present method offers a straightforward approach to synthesize 5-hydroxy-1H-pyrrol-2(5H)-ones from sulfur ylides without the aid of transition metal in one-pot operation, which involves sequential cyclization and rearrangement reaction. The formation of 5-hydroxy-1H-pyrrol-2(5H)-ones is supported by different spectroscopic techniques, including X-ray crystallographic data and 2D NMR studies (COSY, HSQC, HMBC, and DEPT).