An Efficient Synthesis and Base-Promoted Rearrangement of 5-[(1,3-Dioxolan-2-ylmethyl)sulfanyl]-1H-pyrrol-2-amines: Simple Entry to β-[(Pyrrol-2-yl)sulfanyl]-Substituted Monovinyl Ethers of Glycols

The sequential reactions of monolithiated tertiary propargylamines, isothiocyanates, and 2-(bromomethyl)-1,3-dioxolane lead to 5-[(1,3-dioxolan-2-ylmethyl)sulfanyl]-1H-pyrrol-2-amines in up to 91% yield in a single synthetic operation. Under the action of the t-BuOK−DMSO system (r.t., 1 h), the latter rearrange to β-[(pyrrol-2-yl)sulfanyl]-substituted monovinyl ethers of ethylene glycol (through deprotonation of the SCH2 moiety, followed by cleavage of the C–O bond of the 1,3-dioxolane ring and rearrangement of the forming intermediate) as ~60:40 mixtures of E- and Z-isomers.