Generation of polysubstituted 2-pyridinecarboxylic acid derivatives from the reaction of (functionalised) 2-oxa-5-azabicyclo[2.2.2]oct-5-en-3-ones with various nucleophiles

Article abstract of DOI:10.1016/0040-4020(96)00733-8

By selective reaction of the chlorimine function in the adducts 2 from 3,5-dichloro-2H-1,4-oxazin-2-ones and double bond systems, a series of 6-substituted 2-oxa-5-azabicyclo[2.2.2]oct-5-en-3-ones 3 could be generated. Lactone cleavage of the latter with alcohols or amines yielded variously substituted 4,5-dihydro-5-hydroxy-2-pyridinecarboxylic acid derivatives which were dehydrated to afford the corresponding pyridine systems. Some 6-amino substituted 2-pyridinecarboxamides could be obtained in a one step procedure by reacting 2 with Me₃Al/amine.