| CPC C07D 487/04 (2013.01) | 22 Claims |
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1. A process for preparing a compound of formula (I);
![]() wherein:
R1 is a nitrogen protecting group;
R2 is hydrogen or aryl;
X1 is a leaving group or —N(R3)R4;
at least one of R3 and R4 is a nitrogen protecting group, and the other is hydrogen or an independent nitrogen protecting group;
wherein the process comprises reacting a compound of formula (II);
![]() with an oxidant and a copper-based catalyst.
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