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The development of a novel palladium-catalysed amidation approach towards 5,7,8,9-tetrahydropyrimido[4,5- b ][1,4]diazepin-6-one templates is highlighted. The route proceeds through the reaction of an amino amide, generated by 1,4-addition of an amine to an acrylamide, with 5-bromo-2,4-dichloropyrimidine and final palladium-catalysed cyclisation to provide the functionalised scaffold in up to 60% isolated yield over three steps. The route offers efficiency advantages over the previously reported nitro-reduction cyclisation approach to these molecules. It also provides alternative means to introduce bulky alkyl substituents at the amide nitrogen. The application of this route in the synthesis of a variety of analogues is described. |
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