Continuous Flow Synthesis of alpha-Halo Ketones: Building Blocks for Anti-retroviral Agents

New Drug Approvals

Chiral alpha-halo ketones derived from N-protected amino acids are key building blocks for the synthesis of HIV protease inhibitors such as atazanavir used in HAART combination therapy.

Kappe and De Souza have reported a continuous flow through route to these intermediates which utilises a tube-in-tube reactor to introduce diazomethane generated on demand into the reaction stream containing mixed anhydride derivatives of N-protected amino acids. The resulting alpha-diazo ketones are then decomposed with HCl or HBr to afford the corresponding alpha-halo ketones.

This process allows the safe generation, separation and use of diazomethane in a continuous integrated multi-step synthesis of important API intermediates.

The development of a continuous flow process for the multistep synthesis of α-halo ketones starting from N-protected amino acids is described. The obtained α-halo ketones are chiral building blocks for the synthesis of HIV protease inhibitors, such as atazanavir and darunavir. The synthesis starts with…

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