(R)-Benzyl 3-(4-((t-Butoxycarbonyl)amino)-3-(4-phenoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)piperidine-1-carboxylate is an intermediate in synthesizing Ibrutinib-d4 (I124971), a labelled analogue of Ibrutinib (I124970). Ibrutinib is a highly selective Bruton’s tyrosine kinase (Btk) irreversible inhibitor.