I have been checking out the C-sections. The first was Caesar at Los Angeles, born 1st June 1977. His mother, Ellie, had killed her previous two infants immediately after giving birth, so the C-section was performed and he was hand-reared. Ellie had another infant, Brutus, the following year and I presume the same procedure was used.
Zuri at Cheyenne Mountain Zoo was born by C-section on 31st December 1996 because her mother, Juju, was losing blood. There was a reintroduction, but Juju was not a good mother. Zuri was hand-reared and sent to Toronto where she has raised a daughter.
Kambera was born by C-section at Columbus Zoo on 19th February 1999, she was hand-reared for several months before being reared by a surrogate mother, who was actually her grandmother Lulu.
Yakini was born by C-section on 28th November 1999 at Melbourne Zoo and was hand-reared.
Bolingo at Busch Gardens was raised by his mother Kishina after being born by C-section on 18th November 2005. He was reintroduced to her after a few days - we can all hope that Imani will be equally successful in very similar circumstances.
However it doesn't always go well. Female Acacia at North Carolina Zoo had a C-section on 7th July 2013, after being in labour for 24 hours. The infant was reintroduced to her and she was caring for it, but it was found dead in her arms on the 10th: she might have crushed it in the night.
For some reason I haven't found any in Europe, except for the removal of a dead infant in Prague some years ago. I expect that there will have been some.
Alan