Metallation and Functionalisation of Dihydrodipyridopyrazines

We describe the lithiation of the recently prepared 5,10-dimethyl-5,10-dihydrodipyrido[2,3-b:3,2-e] and [2,3-b:2,3-e]pyra-zines 1 (R=CH 3 ) and 2 (R=CH 3 ), respectively. Interestingly while 1 was metallated at the pyridinering, 2 was lithiated at the methyl groups. Reactions with electrophiles led to new functionalised dihydrodipyridopyrazines.