2: 1.) a.) sulfuric acid, sodium nitrite, b.) urea, 2.) tris(2,2'-bipyridyl)ruthenium(II) hexahydrate, copper(II) acetate / 1.) a.) water, from 0 to 5 deg C, 15 min, 2.) 25 deg C, irradiation, 1.5 h View Scheme

2: 1.) a.) sulfuric acid, sodium nitrite, b.) urea, 2.) tris(2,2'-bipyridyl)ruthenium(II) hexahydrate, copper(II) acetate / 1.) a.) water, from 0 to 5 deg C, 15 min, 2.) 25 deg C, irradiation, 1.5 h View Scheme