The research group of prof. Daniel Gryko published the procedure in Organic Syntheses. This procedure describes the preparation of tetraaryl- and hexaaryl-1,4-dihydropyrrolo[3,2-b]pyrroles. This is first procedure originating from Poland published in Organic Syntheses since 1976.
More info: http://orgsyn.org/demo.aspx?prep=v98p0242