Crystal structure, protolytic properties and alkylating activity of 3-(1-amino-ethylidene)-2-methoxy-2-oxo-2,3-dihydro-2l5-benzo[e][1,2] oxaphosphinin-4-one

The crystal structure of 3-(1-amino-ethylidene)-2-methoxy-2-oxo-2,3-dihydro-2l5-benzo[e][1,2]oxaphosphinin-4-one (1a), protolytic properties and alkylating activity were determined. The title compound exists in solid state as a keto-amine form. Compound 1a behaves in 5% v/v 1,4-dioxane–water solution as a monofunctional molecule within pH 3.0–5.0. As determined in an in vitro Preussmann test compound 1a exhibits high (CCC) alkylating activity. The crystal structure of the title compound has been determined by X-ray methods and NMR spectroscopy. The crystals are orthorhombic, space group P212121, with aZ9.296(1), bZ10.169(1), cZ12.694(1) A° , VZ1200.1(2) A° 3, ZZ 4, DcZ1.401 g cmK3, F(000)Z528, TZ153 K f (Mo Ka)Z0.231 mmK1. The molecule adopts the keto-amine tautomeric form with medium strong N–H/O hydrogen bond. A characteristic motif of the crystal packing are ‘zigzag’ chains parallel to b axis. q 2005 Elsevier B.V. All rights reserved