| TECHNOLOGY |
BUT THE butyllithium route to boronic acids has deficiencies in cost, flexibility, and yield, according to R&D manager for Co.'s pharmaceuticals business. Also, some boronic acids are not accessible by the usual chemistries or are unstable and easily lose boron. For these reasons, alternative routes and reagents have been developed. For example, Co. prepares arylboronic acids with an alkyllithium prepared in situ from an alkyl chloride and lithium metal. In the presence of an aryl substrate, the alkyllithium immediately transfers lithium to the aryl compound, which is then replaced by a boronic acid. The method is flexible because the alkyl chloride can be varied. Compounds that could not be prepared with butyllithium become accessible through other alkyllithiums. However, the reaction requires cryogenic conditions. |
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