Photoinduced direct hydration of dipyridylacetylenes in acidic aqueous solution.

Photoinduced direct hydration of dipyridylacetylenes (DPAs) in acidic aqueous solution was achieved upon UV irradiation at room temperature. This is a catalyst-free reaction with moderate-to-good yields, and asymmetric dipyridylacetylenes afford the corresponding Markovnikov addition products.