A boryl-migratory semipinacol rearrangement

The semipinacol rearrangement is one of the classic yet useful synthetic tools in organic synthesis. However, semipinacol rearrangements involving heteroatom-migration are rare. Reported herein is a boryl-migratory semipinacol rearrangement of α-hydroxyallylboronates and α-hydroxypropargylboronates triggered by diverse halogen-, oxygen-, sulfur- and selenium-containing electrophiles. The protocol leads to a mild and facile access to organoborons bearing valuable functionalities. The σ (C—B) hyperconjugation is believed to be the key factor that leads to the observed exclusive chemoselectivity and enhanced reactivity. Synthetic utilities of the formed products were demonstrated.