Convenient Continuous Flow Synthesis of N-Methyl Secondary Amines from Alkyl Mesylates and Epoxides

Multistep Continuous Flow Synthesis of Stavudine

Herein, we demonstrate an elegant multistep continuous flow synthesis for stavudine (d4T), a potent nucleoside chemotherapeutic agent for human immunodeficiency virus, acquired immunodeficiency syndrome (AIDS) and AIDS-related conditions. This was accomplished via six chemical transformations in five sequential continuous flow reactors from an affordable starting material, 5-methyluridine. In the first instance, single step continuous flow synthesis was demonstrated with an average of 97% yield, 21.4 g/h throughput per step, and a total of 15.5 min residence time. Finally, multistep continuous flow synthesis of d4T in 87% total yield with a total residence time of 19.9 min and 117 mg/h throughput without intermediate purification was demonstrated.

Ru-Catalyzed Selective Catalytic Methylation and Methylenation Reaction Employing Methanol as the C1 Source

Methanol can be employed as a green and sustainable methylating agent to form C-C and C-N bonds via borrowing hydrogen (BH) methodology. Herein we explored the activity of the acridine-derived SNS-Ru pincer for the activation of methanol to apply it as a C1 building block in different reactions. Our catalytic system shows great success toward the β-C(sp³)-methylation reaction of 2-phenylethanols to provide good to excellent yields of the methylated products. We investigated the mechanistic details, kinetic progress, and temperature-dependent product distribution, which revealed the slow and steady generation of in situ formed aldehyde, is the key factor to get the higher yield of the β-methylated product. To establish the environmental benefit of this reaction, green chemistry metrics are calculated. Furthermore, dimerization of 2-naphthol via methylene linkage and formation of N-methylation of amine are also described in this study, which offers a wide range of substrate scope with a good to excellent yield.