Diastereoselective Homocoupling of Benzylic C(sp<sup>3</sup>)–H Bonds Enabled by Halogen Transfer

A transition-metal-\nand harsh-oxidant-free strategy for diastereoselective\nhomocoupling of benzylic α-boryl carbanions has been developed.\nCentral to this methodology is the ability of the halogen transfer\nreagent to seamlessly integrate halogenation and substitution within\na compatible process. Additionally, this methodology is also applicable\nto the homocoupling of diarylmethanes and alkylheteroarenes. Substrates\nbearing oxidatively sensitive functional groups were well-tolerated.\nPreliminary studies suggest that the hydrogen bond between two boryl\ngroups contributes to the high diastereoselectivities.