Sulfated polyborate-H2O assisted tunable activation of N-iodosuccinimide for expeditious mono and diiodination of arenes

Abstract

Owing to both Lewis and Bronsted acid active sites on sulfated polyborate under homogenous conditions, we were keen on developing iodination protocol of arenes that can meet the requirement of regioselectivity and higher yield. The sulfated polyborate activates N-iodosuccinimide for mono iodination of highly activated substrates viz. phenols, anilines under anhydrous condition. Water tunes sulfated polyborate to generate more Bronsted acid sites resulting in rapid activation of NIS for diiodination. The protocol was equally applicable to diiodination of 4-hydroxyphenylacetic acid to synthesize 4-hydroxy-3,5-diiodophenylacetic acid, an intermediate of tiratricol, a thyroid treatment drug. This protocol was further integrated via one-pot sequential iodination and Sonogashira coupling to synthesize aryl acetylenes, building blocks for the synthesis of a variety of specialty chemicals, API, and natural products.