The History of Flow Chemistry at Eli Lilly and Company.

Flow chemistry was initially used for speed to early phase material delivery in the development laboratories, scaling up chemical transformations that we would not or could not scale up batch for safety reasons. Some early examples included a Newman Kwart Rearrangement, Claisen rearrangement, hydroformylation, and thermal imidazole cyclization. Next, flow chemistry was used to enable safe scale up of hazardous chemistries to manufacturing plants. Examples included high pressure hydrogenation, aerobic oxidation, and Grignard formation reactions. More recently, flow chemistry was used in Small Volume Continuous (SVC) processes, where highly potent oncolytic molecules were produced by fully continuous processes at about 10 kg/day including reaction, extraction, distillation, and crystallization, using disposable equipment contained in fume hoods.

Scalable Synthesis of Enantiopure Bis-3,4-diazaphospholane Ligands for Asymmetric Catalysis.

An optimized route to enantiopure tetra-carboxylic acid and tetra-carboxamide bis(diazaphospholane) ligands that obviates chromatographic purification is presented. This synthesis, which is demonstrated on 15 and 100 g scales, features a scalable classical resolution of tetra-carboxylic acid enantiomers with recycling of the resolving agent. When paired with a rhodium metal center, these bis(diazaphospholane) ligands are highly active and selective in asymmetric hydroformylation applications.

Development of Pd/C-catalyzed cyanation of aryl halides.

A practical method for palladium-catalyzed cyanation of aryl halides using Pd/C is described. The new method can be applied to a variety of aryl bromide and active aryl chloride substrates to effect efficient conversions. The process features many advantages over existing cyanation conditions and the practical utility of the process has been demonstrated on scale.

Perpetrator Risk Markers for Intimate Terrorism and Situational Couple Violence: A Meta-Analysis.

Johnson developed a typology of intimate partner violence (IPV) which includes two different categories of violence: situational couple violence (SCV) and intimate terrorism (IT). Johnson proposed that IT is more likely to be found in clinical samples (e.g., batterer intervention programs or domestic violence shelters) compared to nonclinical (general population) samples. This meta-analysis (n = 149 studies; k = 216 effect sizes) examines differences in the strengths of IPV risk markers in clinical and nonclinical samples of male perpetrators and female victims. All variables (communication and conflict resolution, demand-withdraw patterns, relationship dissatisfaction, controlling behaviors, jealousy, patriarchal beliefs, power in the relationship, and stalking) were expected to be significantly related to IPV for both clinical and nonclinical populations. However, specific variables indicative of IT (control, jealousy, patriarchal beliefs, power, and stalking) were expected to be more strongly associated with clinical samples compared to nonclinical samples. As expected, most variables were significant for clinical and nonclinical populations, and IT risk markers (control, power, jealousy, and patriarchal beliefs) were significantly stronger risk markers for IPV in clinical samples. These results indicate that Johnson's typology may be conceptualized as representing a continuum of violence, with IT being more severe due to the controlling nature of the violence. Sample type needs to be considered when research about IPV is disseminated, as different degrees of IPV (IT vs. SCV) may be present depending on sample type. Implications from this study include the need to differentiate the level of violence and to tailor intervention for IPV appropriately.

Continuous Platform to Generate Nitroalkanes On-Demand (in situ) using Peracetic Acid-Mediated Oxidation in a PFA Pipes-in-Series Reactor.

The synthetic utility of the aza-Henry reaction can be diminished on scale by potential hazards associated with the use of peracid to prepare nitroalkane substrates, and the nitroalkanes themselves. In response, a continuous and scalable chemistry platform to prepare aliphatic nitroalkanes on-demand is reported, using the oxidation of oximes with peracetic acid and direct reaction of the nitroalkane intermediate in an aza-Henry reaction. A uniquely designed pipes-in-series plug flow tube reactor addresses a range of process challenges including stability and safe handling of peroxides and nitroalkanes. The subsequent continuous extraction generates a solution of purified nitroalkane which can be directly used in the following enantioselective aza-Henry chemistry to furnish valuable chiral diamine precursors in high selectivity, thus, completely avoiding isolation of potentially unsafe low molecular weight nitroalkane intermediate. A continuous campaign (16 h) established that these conditions were effective in processing 100 g of the oxime and furnishing 1.4 L of nitroalkane solution.

Kilogram-scale prexasertib monolactate monohydrate synthesis under continuous-flow CGMP conditions.

Advances in drug potency and tailored therapeutics are promoting pharmaceutical manufacturing to transition from a traditional batch paradigm to more flexible continuous processing. Here we report the development of a multistep continuous-flow CGMP (current good manufacturing practices) process that produced 24 kilograms of prexasertib monolactate monohydrate suitable for use in human clinical trials. Eight continuous unit operations were conducted to produce the target at roughly 3 kilograms per day using small continuous reactors, extractors, evaporators, crystallizers, and filters in laboratory fume hoods. Success was enabled by advances in chemistry, engineering, analytical science, process modeling, and equipment design. Substantial technical and business drivers were identified, which merited the continuous process. The continuous process afforded improved performance and safety relative to batch processes and also improved containment of a highly potent compound.

A selective estrogen receptor modulator for the treatment of hot flushes.

A selective estrogen receptor modulator (SERM) for the potential treatment of hot flushes is described. (R)-(+)-7,9-difluoro-5-[4-(2-piperidin-1-ylethoxy)phenyl]-5H-6-oxachrysen-2-ol, LSN2120310, potently binds ERalpha and ERbeta and is an antagonist in MCF-7 breast adenocarcinoma and Ishikawa uterine cancer cell lines. The compound is a potent estrogen antagonist in the rat uterus. In ovariectomized rats, the compound lowers cholesterol, maintains bone mineral density, and is efficacious in a morphine dependent rat model of hot flush efficacy.

Development of an Intermittent-Flow Enantioselective Aza-Henry Reaction Using an Arylnitromethane and Homogeneous Brønsted Acid-Base Catalyst with Recycle.

A stereoselective aza-Henry reaction between an arylnitromethane and Boc-protected aryl aldimine using a homogeneous Brønsted acid-base catalyst was translated from batch format to an automated intermittent-flow process. This work demonstrates the advantages of a novel intermittent-flow setup with product crystallization and slow reagent addition which is not amenable to the standard continuous equipment: plug flow tube reactor (PFR) or continuous stirred tank reactor (CSTR). A significant benefit of this strategy was the integration of an organocatalytic enantioselective reaction with straightforward product separation, including recycle of the catalyst, resulting in increased intensity of the process by maintaining high catalyst concentration in the reactor. A continuous campaign confirmed that these conditions could effectively provide high throughput of material using an automated system while maintaining high selectivity, thereby addressing nitroalkane safety and minimizing catalyst usage.

Rhodium-catalyzed and zinc(II)-triflate-promoted asymmetric hydrogenation of tetrasubstituted α,ß-unsaturated ketones.

The asymmetric hydrogenation of tetrasubstituted α,ß-unsaturated ketones has been accomplished using an in situ formed rhodium-Josiphos catalyst. The reaction is enhanced by addition of catalytic zinc(II) triflate, which significantly improves turnover frequency while suppressing epimerization of the products.