Dichloromethylation of Nitrobenzene Derivatives via Vicarious Nucleophilic Substitution of Hydrogen with Trichloromethyl Carbanions in Flow

In recent years indigo compounds have been adopted across a wide range of applications. Of particular note is their introduction as organic semi-conductors. As this field grows, so does the desire to probe the structure of these compounds, to generate semi-conductors with favourable charge transport properties. One of the strategies employed to achieve this, is the functionalisation of the core indigo structure. This can be executed through the use of functionalised nitro benzaldehyde starting materials, generated via hydrolysis of dichloro methylated intermediates. However, these compounds are often costly to purchase or are not commercially available, as such it would be favourable to establish a procedure for the cost-effective generation of the aldehyde starting materials at scale. Herein we report a procedure for the cost-effective synthesis of the dichloro methylated nitroarene intermediates on a gram scale, through the use of vicarious nucleophilic substitution and flow chemistry, enabling simplified access to a variety of halogenated nitro benzaldehydes. Potentially facilitating the generation, and investigation, of a range of indigo semi-conductors with increased structural diversity.