Identify the reagents 4: answers

Last month I posted a scheme for the synthesis of a late-stage intermediate towards AZD9833, a compound identified by AstraZeneca as a selective estrogen receptor degrader (SERD) and antagonist that is currently in phase 2b clinical trials for the treatment of ER+ breast cancer. I asked if you could identify reagents or intermediates A-C. Below are the answers! You can read more here in the full reference: J. Scott et al, J. Med. Chem. 2020, 63, 14530–14559