Synthesis of gem-Difluoroalkenes via a Sequence of Hydroboration and 1,2-Elimination of α,β-Unsaturated Carbonyls

Abstract

We reported a simple protocol for the synthesis of gem-difluoroalkenes via a reaction sequence of hydroboration and 1,2-elimination of α,β-unsaturated carbonyl substrates under mild conditions. Two steps of this method could be executed in one pot. The β-CF2H- and β-CFH2-α,β-unsaturated carbonyls can be obtained smoothly from the α,β-unsaturated gem-difluoroamide with NaH as the base and via a boration–1,2-elimination sequence.

Copper-catalyzed Markovnikov hydroboration of aliphatic terminal alkenes using carbonyl as a weak directing group

“…5 Transition metal-catalyzed hydroboration of alkenes 6 could be considered as a straightforward and efficient method for the synthesis of this class of organoboron compounds. Metal-catalyzed hydroboration of activated alkenes, 7 such as aryl alkenes, 8 has been well established with good regioselectivity to deliver (anti)Markovnikov organoboron compounds. In sharp contrast, the hydroboration protocol of simple unactivated aliphatic alkenes was typically plagued by lower reactivity as well as poor regiochemical differentiation, generally leading to unsatisfactory regioselectivity.…”