Pharmaceutical manufacturing typically uses batch processing at multiple locations. Disadvantages of this approach include long production times and the potential for supply chain disruptions. As a preliminary demonstration of an alternative approach, we report here the continuous-flow synthesis and formulation of active pharmaceutical ingredients in a compact, reconfigurable manufacturing platform. Continuous end-to-end synthesis in the refrigerator-sized [1.0 meter (width) × 0.7 meter (length) × 1.8 meter (height)] system produces sufficient quantities per day to supply hundreds to thousands of oral or topical liquid doses of diphenhydramine hydrochloride, lidocaine hydrochloride, diazepam, and fluoxetine hydrochloride that meet U.S. Pharmacopeia standards. Underlying this flexible plug-and-play approach are substantial enabling advances in continuous-flow synthesis, complex multistep sequence telescoping, reaction engineering equipment, and real-time formulation.

In a total residence time of three minutes, ibuprofen was assembled from its elementary building blocks with an average yield of above 90% for each step. A scale-up of this five-stage process (3 bond-forming steps, one work-up, and one in-line liquid-liquid separation) provided ibuprofen at a rate of 8.09 g h(-1) (equivalent to 70.8 kg y(-1)) using a system with an overall footprint of half the size of a standard laboratory fume hood. Aside from the high throughput, several other aspects of this synthesis expand the capabilities of continuous-flow processing, including a Friedel-Crafts acylation run under neat conditions and promoted by AlCl3, an exothermic in-line quench of high concentrations of precipitation-prone AlCl3, liquid-liquid separations run at or above 200 psi to provide solvent-free product, and the use of highly aggressive oxidants, such as iodine monochloride. The use of simple, inexpensive, and readily available reagents thus affords a practical synthesis of this important generic pharmaceutical.

A continuous end-to-end synthesis and purification of diphenhydramine hydrochloride featuring atom economy and waste minimization is described. Combining a 1 : 1 molar ratio of the two starting material streams (chlorodiphenylmethane and N,N-dimethylaminoethanol) in the absence of additional solvent at high temperature gives the target compound directly as a molten salt (ionic liquid above 168 C) in high yield. This represents the first example of continuous active pharmaceutical ingredient (API) production in this manner. Six of the twelve principles of green chemistry as defined by the American Chemical Society are achieved, most prominently waste minimization and atom economy. Fig. 1 Continuous end-to-end synthesis, purification, and crystallization of diphenhydramine hydrochloride (2).

A two-step route to MK-4482 (EIDD-2801, 1) was developed consisting of an esterification and hydroxamination of cytidine. The selective acylation and direct amination eliminate the need for protecting and activating...