A convenient and selective way of forming a carbon-carbon double bond is through the Wittig reaction and its modifications. Conventionally, this reaction is a two-step process, where the Wittig salt is treated with a base to obtain the reactive phosphonium ylide species, with subsequent workup and addition of the aldehyde. Using base-stable compounds, the reaction can be performed as a one-pot procedure as well. In batch, this two-phase system suffers from irreproducibility issues due to uncontrollable mixing behaviour. In continuous flow chemistry, this translates to a plug-flow system with the advantage of added control over the two-phase system.

Wittig reaction to form tert-Butyl cinnamate

As a feasibility study, FutureChemistry has translated this reaction from a batch process to a continuous flow process. FutureChemistry’s typical three-tier approach led to a protocol which can be adapted to any viable substrate:

      1) Translation of batch process to continuous flow process:
           a) Stock solutions approach, yielding a homogeneous reaction mixture.
           b) Quenching solution to follow the reaction in time.
           c) Flow markers approach to accurately assess reaction parameters.
      2) Automated reaction optimisation.
      3) Out scaling to preparative synthesis

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