Efficient Construction of Highly Functionalized Pyrrolo[1,2-c]imidazol-1-ones via a Regioselective 1,3-Dipolar Cycloaddition of Imidazolidin-4-ones, Aldehydes, and Nitroalkenes in One Pot.

A series of novel pyrrolo[1,2-c]imidazol-1-ones were efficiently synthesized via a three-component, regioselective 1,3-dipolar cycloaddition reaction. The azomethine ylides generated in situ from imidazolidin-4-ones and aldehydes reacted with the nitroalkenes to yield the novel pyrrolo[1,2-c]imidazol-1-one derivatives with multiple stereogenic centers in moderate to high yields (up to 99%) and in high diastereoselectivities (up to 98:2). The structure and relative stereochemistry of cycloadducts were confirmed by 1H NMR spectroscopy and X-ray crystallography.