The use of a�hydroxy acids (AHAs) in the cosmetic industry is well known and these compounds are often present in products which claim to reduce wrinkles. In this contribution, the spinning tube-in-tube (STT�) continuous-flow reactor was used for the intensified synthesis of a�hydroxy acids from amino acids via a diazotization reaction in a highly mixed environment (Scheme 1). This continuous-flow reactor provides an opportunity for the in situ production of reactive species in a small volume; thereby reducing the safety concern associated with diazonium salts. The STT� reactor demonstrated to be advantageous in in situproduction of the nitrosonium ion by allowing it to react with the amine prior to decomposition. Conversions of the starting materials are over 85% even with a very short residence time within the reaction zone of the reactor.Additionally, the STT� reactor was also used for the synthesis of amides via the Ritter reaction also in a highly mixed environment (Scheme 2). This acid-promoted nucleophilic attack of a nitrile on a carbocation followed by hydrolysis of the nitrilium ion results an amide. In a recent survey of pharmaceutical reactions to prepare drug candidates, amide bond formation was identified as a step in the synthesis of 65% of the candidates examined. This acid-catalyzed continuous-flow reaction was achieved in very short residence times (< 180 s) and affording the respective products in high yields.

Rapid synthesis of a-hydroxy acids and N-alkyl amides in the continuous-flow spinning tube-in-tube (STT<sup>�</sup>) reactor

248th National Meeting (2014)

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Rapid synthesis of a-hydroxy acids and N-alkyl amides in the continuous-flow spinning tube-in-tube (STT�) reactor

Rapid synthesis of a-hydroxy acids and N-alkyl amides in the continuous-flow spinning tube-in-tube (STT^�) reactor