Identify the reagents 4: July 2021

The scheme below shows 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. Can you identify reagents or intermediates A, B and C? Answers and a reference will be posted in late July, along with another problem. Enjoy!