REACTION BETWEEN 2-PHENYL-1,1-DICYANOALLYL ANION AND N-METHYL-2,2-DIMETHYLPROPIONITRILIUM AND 1,N-2,N-2-TRIMETHYL-2,2-DIMETHYLPROPIONYLAMIDINIUM TRIFLUOROMETHANESULFONATES

The reaction of 2-phenyl-1,1-dicyanoallyl anion with N-methyl-2,2-dime thyl-propionitrilium ion (2) in acetonitrile solution resulted in form ation of dimethyl-1-phenyl-2-pentenylidene]propanedinitrile (6), which at elevated temperature (25-50 degrees C, depending on the solvent) u ndergoes a ring closure to methylamino)-3-cyano-4-phenyl-6-tert-butylp yridine (7) or in the presence of aqueous acid to 3-cyano-4-phenyl-6-t ert-butyl-2-pyrone (8). Using N,N-dimethylformamide as solvent, in add ition to 7, two other compounds are formed, viz. ylamino)-1-phenyl-2-p ropenylidene)propanedinitrile (9) and N-(4,4-dicyano-3-phenyl-1, 3-but adienyl)-N,2,2-trimethylpropanamide (10). The latter two compounds are results of a primary reaction of the title nitrilium ion with the sol vent to give ,N-2-trimethyl-N-1-2,2-dimethyl-propionylamidinium triflu oromethanesulfonate (11) which in turn reacted with the title allyl an ion 2 to give 9 and 10, for which X-ray crystal structures were determ ined. Strong indications of a tetrahedral mechanism in the reaction of 2 with 11 are presented.