Microwave-assisted synthesis of ethynylarylboronates for the construction of boronic acid-based fluorescent sensors for carbohydrates

A reliable and operationally simple procedure for the synthesis of 2,2-dimethylpropane-1,3-diyl ethynylaryl boronates 4 was developed. The key step is microwave-facilitated selective formation of 2,2-dimethylpropane-1,3-diyl trimethylsilylethynylaryl boronates by Sonogashira reaction from the corresponding bromides. The use of microwave was found to significantly improve the reaction yield and shorten the reaction time. The 2,2-dimethylpropane-1,3-diyl ethynylaryl boronates 4 prepared can be used in the construction of diboronic acid libraries through [2+3] Huisgen cycloaddition for carbohydrate fluorescent sensor development.