The development of a convergent, chromatography-free synthesis of an allosteric Akt kinase inhibitor is described. The route comprised 17 total steps and was used to produce kilogram quantities of the target molecule. A key early transformation, for which both batch and flow protocols were developed, was formylation of a dianion derived by deprotonation and subsequent lithium-halogen exchange from a 2-bromo-3-aminopyridine precursor. Improved reaction yield and practicality were achieved in the continuous processing mode. Further significant process developments included the safe execution of a high temperature and pressure hydrazine displacement, separation of substituted cyclobutane diastereomers by means of chemoselective ester hydrolysis, and a late-stage Suzuki fragment coupling under mild conditions. ■ RESULTS AND DISCUSSIONSynthesis of Triflate 4. Pyridyl aldehyde 5 was previously prepared on gram scale in 5 steps from picoline derivative 9. 6 A

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The individual isomers of methyl 1-amino-3-(4-bromophenyl)cyclopentanecarboxylate are useful intermediates for the synthesis of S1P1 receptor agonists. Herein we describe a scalable synthesis and isolation of each of the four stereoisomers of this compound in gram quantities with >98% ee and de. The utility of this approach is demonstrated by the synthesis of ((1R,3R)-1-amino-3-(4-octylphenyl)cyclopentyl)methanol in 7 steps, 11% overall yield, and >98% ee and de.

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