CO-CYCLIZATION OF ETNCO AND ME2CO AS THE RESULTS OF THEIR SELECTIVE INSERTION INTO THE NIOBIUM-CHLORINE BOND

Abstract

Development of the new methods for drug production is impossible without reliance on the novel and unorthodox approaches to the synthesis of heterocyclic complexes and compounds.The method is based on the study of new aspects of the of two types of behavior of the coordinated molecules in reaction - their ability to insert into the same transition metal-halogen bond, and their ability to form the unusual heterocyclic ligands, or even molecules after leaving the complex’s coordination sphere. This will make it possible not only to synthesize the already-known compounds under milder conditions, but to also obtain new ones as products of such mixed condensation reactions. On the one hand, this opens up new possibilities for designing and performing the intraspherical "stitching" of ligands and their synthesis with high efficiency and selectivity. 
 On the other hand, these reactions can be considered a significant contribution to the fundamental coordination chemistry in terms of illustration of the new modalities of the mutual influence of ligands, namely their ability to stimulate each other for a mutual insertion, and sheds light on the mechanisms of the intraspheric condensation. Oxadiazine derivatives, just like the derivatives of triazine we synthesized and reported previously, could become a foundation for the generation of biologically-active compounds, often containing heterocyclic fragments and frequently used for the treatment of malignant tumors. It can be expected that the developed method will find use in the synthesis of the new classes of potential antitumor compounds.
 We have previously found that organic isocyanate not only themselves insert into M-Hal bond, but can also activate the insertion of acetonitrile, the resulting heteromolecular chain of inserted molecules being composed of two MeNCO and one MeCN fragments. Such a structure of this complexes was confirmed be synthesis of striazine derivatives on their base. In this work was to determine optimum condition for the insertion of ethyl isocyanate with acetone into niobium-chlorine bond, as well as their subsequent mixed co-cyclization with obtaining of oxadiazine derivative.