In order to search for novel antitumor and antiviral agents with high activity and love toxicity, some 2-propyl-5-(substituted)phenyl-1,4-dioxo-1,2,3, 4, 5, 6, 7, 8-octahydro-[1,4,2]diazaphosphorino[1,2-a] [1,3,2]benzodiazaphosphorine 3-oxides (2a-e) have been designed incorporating the proximate carbonyl and phosphoryl groups into the benzoannulated phosphadiamide heterocycle and synthesized in acceptable yields. These compounds contain the proximate carbonyl and phosphoryl groups in the fused heterocycle. Their structures were confirmed by spectroscopic methods and microanalyses. The results from X-ray crystallography analysis of 2a showed that the proximate carbonyl and phosphoryl groups are not coplanar because of their being jointly located in the fused heterocycle, having ring tension, and this then destroys the conjugation between the C=O and the P=O moieties. As a result, the length of the P-C bonds measured as 1.851(3)-1.852(3) Angstrom are just the same as that of a P-C bond not involved in conjugation (1.80-1.85 Angstrom). Also, the C(1), C(2), C(3), N(2), N(3), and P(1) atoms of the [1,4,2]diazaphosphorino moiety exist preferably in the boat conformation. The coplanar C(1), C(3), N(2), and N(3) atoms, within an average deviation of 0.0102 Angstrom, form the ground floor of the boat conformation, whereas the P(1) and C(2) atoms are on the same side of the coplanar structure with the distance of 0.7067 and 0.6315 Angstrom, respectively. (C) 2002 John Wiley Sons, Inc.
