Iridium-Catalysed C-H Borylation of 2-Pyridones; Bisfunctionalisation of CC4
The high regioselectivity associated with the iridium-catalysed borylation of pyridones has been exploited to provide a very direct and efficient entry to C(10) doubly substituted CC4 variants of cytisine. Two approaches have been evaluated based on (i) C-H activation of cytisine (or an N-substituted derivative) followed by N-alkylation (to enable dimer formation) and (ii) direct C-H activation and borylation of CC4 itself. Both approaches provide access to C(10)-functionalized CC4 derivatives, but direct borylation of CC4 allows for a wider range of functional group interconversions to be tolerated.
Honraedt, Aurélien,Niwetmarin, Worawat,Gotti, Cecilia,Campello, Hugo Rego,Gallagher, Timothy
p. 3420 - 3429
(2018/07/13)
BROMINATION OF 1-ALKYL-2-PYRIDONES
The corresponding monobromides were obtained in the bromination of 1-alkyl-2-pyridones with bonded bromine (with N-bromosuccinimide and dioxane dibromide).The conditions under which the yields of the mixtures of isomers were 60-80percent, and almost no dibromides were obtained, were found.It was established that the ratios of the 3- and 5-bromo isomers depend on the character of the brominating agent.