Ibrutinib Impurity 42

1,5-Dihydro-1-[(3R)-1-(1-oxo-2-propen-1-yl)-3-piperidinyl]-3-(4-phenoxyphenyl)-4H-pyrazolo[3,4-d]pyrimidin-4-one may be useful in the process for the preparation of 1-[(3R)-3-[4-amino-3-(4-phenoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidin-1-yl]-1-piperidinyl]-2-propen-1-one and polymorphs thereof.