Reductive coupling of azonaphthalenes for the synthesis of BINAMs <i>via</i> a diboron-enabled [5,5]-sigmatropic rearrangement

The [5,5]-sigmatropic rearrangement is a less-studied reaction and may be strategically utilized to devise unique synthetic processes. Herein, we document a diboron-enabled [5,5]-sigmatropic rearrangement for practical synthesis of BINAM derivatives. Mechanistically, a concerted activation of azonaphthalenes by diboron creates a unique ten-membered transition state, which subsequently triggers a [5,5]-sigmatropic rearrangement. The reaction occurs under mild conditions, and offers operational simplicity, remarkable chemo- and regioselectivities, and good scalability (>10 grams).