The Ireland-Claisen Rearrangement is a well-known reaction and powerful tool in organic synthesis.  It enables the formation of g,d-unsaturated acids from their corresponding allylic esters by [3,3] sigmatropic rearrangement.  Typically, the allylic ester is subjected to a strong base to form the enolate ester, which can then readily rearrange to produce the desired product.  Even though this rearrangement was an improvement from previous Claisen reactions (harsh conditions, low yields), it still employed long reaction times and reagents that required special handling, such as alkyl lithiums and air-sensitive catalysts.  To overcome these obstacles, we have utilized continuous flow microreactors to aid in lowering reaction times and minimize handling of reagents.  Flow chemistry is an emerging technology that has shown a wide-range of benefits in organic chemistry, such as efficient mixing and heat transfer, increased reaction kinetics, as well as the ability to develop automated variants.  Initial results have shown reduced reaction times for the standard rearrangement conditions.  Optimizations as well as enantioselective Ireland-Claisen rearrangements in a continuous flow microreactor process will be presented.

Ireland-Claisen rearrangements in a continuous flow process

245th National Meeting (2013)

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