Processes for preparing indeno[1,2-E][1,3,4]oxadiazine-dicarboxylates

Abstract

Oxadiazines of formula I, wherein R 1 is F, Cl or fluoroalkoxy and R 2 is alkyl, are prepared by reacting hydrazine derivatives of formula II with a dialkoxymethane in the presence of a protic acid catalyst in an inert solvent under conditions which allow for the prompt removal of the alcohol by-product by distillation. The reaction can be combined with the preparation of the hydrazines derivatives II from the corresponding ketones and hydrazines NH 2 -NHR 3 in the presence of the same protic acid catalyst and an inert solvent. Oxadiazines I are useful as intermediates in the preparation of arthropodicidal agents.

What is claimed is:  
     
       1. A process for the preparation of a dicarboxylate oxadiazine of Formula I                    
       which is racemic or enantiomerically enriched at the chiral center*, 
       wherein: 
       R 1  is F, Cl or C 1 -C 3  fluroalkoxy and R 2  is C 1 -C 3  alkyl comprising reacting a hydrazine carboxylate of Formula II                    
       with at least one molar equivalent of a di(C 1 -C 3  alkoxy) methane in the presence of a protic acid catalyst in an inert solvent under conditions which allow for the prompt removal of the by-product alcohol by distillation. 
     
     
       2. A process of claim  1  wherein R 1  is Cl and R 2  is CH 3 . 
     
     
       3. A process of claim  1  wherein the protic acid is selected from p-toluenesulfonic acid, mixtures of the isomeric toluene sulfonic acids, benzene sulfonic acid, napthalene sulfonic acids, xylene sulfonic acids, methanesulfonic acid, sulfuric acid and camphor sulfonic acids. 
     
     
       4. A process of claim  1  wherein a catalytic amount of the protic acid is used. 
     
     
       5. A process of claim  1  wherein the dialkoxy methane used is a di(C 2 -C 3  alkoxy) methane. 
     
     
       6. A process of claim  1  wherein the reaction temperature is from about 40-150° C. and at a pressure of about 1 atmosphere. 
     
     
       7. A process of claim  1  wherein the solvent is an inert non-halogenated solvent. 
     
     
       8. A process for preparing a compound of Formula I                    
       which is racemic or enantiomerically enriched at chiral center* 
       wherein: R 1  is F, Cl, or C 1 -C 3  fluoroalkoxy, and R 2  is C 1 -C 3  alkyl, comprising:  
       (a) reacting a compound of Formula III, which is racemic or enantiomerically enriched at*,                    
       with the compound of Formula IV in the presence of a protic acid catalyst in an inert solvent 
       
         
           H 2 N—NHCO 2 CH 2 (C 6 H 5 )   IV  
         
       
       to form a compound of Formula II                    
       and (b) reacting the compound of Formula II with a di(C 1 -C 3  alkoxy) methane in the presence of the same protic acid catalyst and inert solvent as used in step (a) under conditions which allow for the prompt removal of the by-product alcohol by distillation. 
     
     
       9. A process of claim  1  further comprising the preparation of an arthropodicidal insecticide of Formula VII by 
       (a) hydrogenating the compound of Formula I to form a compound of Formula V                    
       (b) reacting the compound of Formula V with the compound of Formula VI                    
       to form a compound of Formula VII having substantially the same absolute configuration as the compound of Formula I.