Novel domino reaction of N-(cyanomethyl)-5,10-dihydro[1]benzosilano[3,2-c]pyridinium salts with salicylaldehydes

The synthesis of benzosilanochromenoimidazopyridines was accomplished by a domino reaction of 5,5-dimethyl-10-oxoand 10-hydroxy-10-allyldihydrobenzosilanopyridinium N-cyanomethyl salts with salicyland 5-bromosalicylaldehydes. It was found that in the case of the 10-allyl-10-hydroxydihydrobenzosilanopyridinium salts the reaction occurred at both -positions of the pyridine fragment to form a mixture of the isomeric benzosilano[3,2-c]and benzosilano[2,3-d]chromenoimidazopyridines.