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Slocum D.W.,Western Kentucky University | Slocum D.W.,KinetiChem Inc. | Reinscheld T.,Western Kentucky University | Austin N.,Western Kentucky University | And 2 more authors.
Synthesis (Germany) | Year: 2012

With the advent of flow chemistry, the norm has been reactions executed on the laboratory scale with flow rates of only a few mL/min. We bring to the community's attention our investigation of the halogen-lithium (X-Li) exchange in a continuous flow reactor, the Synthetron™. This novel reactor is capable of orders of magnitude greater rates of flow than current microreactors. This paper details a problematic X-Li exchange using our promoted hydrocarbon media formulated batch studies as well as the comparative derived flow studies. All of these studies have the additional feature of being performed at ambient or near-ambient temperatures. From the initial discoveries of Wittig and Gilman in the late 1930s, it has been known that X-Li exchange of p-bromoanisole (p-BrA) is plagued by a secondary ortho-lithiation. Fine-tuning of promoted hydrocarbon media batch studies can increase the ratio of p-LiA/o-Li-p-BrA; results from the Synthetron™ studies afford a much superior ratio of >100:1. Gram quantities of derivatives from this exchange (employing two reactors) can be prepared in a few seconds. Rationales for these observations will be presented as well as initial studies and discussion for bromobenzene (PhBr), m-bromoanisole (m-BrA), and p-iodoanisole (p-IA). © Georg Thieme Verlag Stuttgart · New York.

Slocum D.W.,Western Kentucky University | Kusmic D.,Western Kentucky University | Raber J.C.,KinetiChem Inc. | Reinscheld T.K.,Western Kentucky University | Whitley P.E.,Western Kentucky University
Tetrahedron Letters | Year: 2010

The halogen/lithium (X/Li) exchange's usefulness is challenged by the extreme conditions employed during the conversion of a bromo or an iodo substituent to an organolithium intermediate. Our preliminary disclosure reveals that simple X/Li exchanges can be accomplished at ambient temperature and in doped hydrocarbon media using n-BuLi. Use of a continuous reactor featuring brief reaction times (≤1 s) and large product throughputs further facilitates the production of a product resulting from a sequential X/Li exchange and nucleophilic addition. © 2010 Elsevier Ltd. All rights reserved.

Slocum D.W.,Western Kentucky University | Slocum D.W.,KinetiChem Inc. | Tekin K.C.,Western Kentucky University | Nguyen Q.,Western Kentucky University | And 5 more authors.
Tetrahedron Letters | Year: 2011

Regiospecific iodination of aryl amines, that is, aryl compounds possessing strong electron donating groups (EDG's) in the p-position, is described. This procedure features not only the unique use of hydrocarbon media for such substitutions but also the absence of any oxidants aside from iodine itself. Further potential of this hydrocarbon media based electrophilic aromatic substitution is demonstrated by the coupling of the iodination with an in situ halogen/lithium exchange and product forming nucleophilic addition in a batch process. The protocol was ultimately scaled to a continuous flow reactor using an isolated p-iodoarylamine. Constituted as described, these procedures possess enhanced atom-economical, green and safety aspects compared to existing literature protocols. © 2011 Elsevier B.V. All rights reserved.

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