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).