Practical Transition-Metal-Free Protodeboronation of Arylboronic Acids in Aqueous Sodium Hypochlorite

Abstract

A concise and practical method was developed for the protodeboronation of arylboronic acids under mild conditions in aqueous NaClO at 100 °C. The strategy is low-cost, transition-metal-free, and base-free.

Key words

protodeboronation - arylboronic acids - sodium hypochlorite

• References and Notes

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• 14 Protodeboronation of Arylboronic Acids; General Procedure A solution of the appropriate arylboronic acid (1 mmol) and TBAB (64 mg, 0.2 mmol) in 10.5 wt% aq NaClO was stirred at 100 °C for 6–12 h until the reaction was complete (TLC). The mixture was extracted with Et₂O (2 × 5 mL), and the organic layer was dried (Na₂SO₄) and concentrated in vacuo. The residue was purified by column chromatography [silica gel, PE–EtOAc (40:1 to 20:1)]. 1,4-Dimethoxybenzene (2a) Prepared from 1a according to the general procedure as a white solid; yield: 121 mg (88%); mp 51–53 °C. ¹H NMR (400 MHz, CDCl₃): δ = 6.86 (s, 4 H), 3.78 (s, 6 H).