Abstract Symmetrical N-heterocyclic 1, 1′, 3, 3′-tetrahydro-2, 2′-bi-1, 3, 2- diazaphospholes and 2, 2′-bi-1, 3, 2-diazaphospholidines are prepared by time-saving, sequential “one-pot” syntheses starting from 1, 4-diazabutadienes or N-alkyl or N-aryl- substituted ethane-1, 2-diamines. This method offers high selectivity and minimizes the loss of products owing to unwanted hydrolysis, and thus grants high product yields. In some ...