An efficient and novel route to (3R)-3-aminoazepane (1) is described. The target is obtained with 99.92% purity, 99.2% ee in seven steps, and 46.2% overall yield. This improved method involves a practical biocatalytic transformation with ωtransaminase to establish the stereogenic center high efficiently as a key step. The developed process was scalable, cost-effective, with a simplified reaction workup, avoiding the use of expensive metal catalyst or chromatography, and commercially viable for the synthesis of 1.

A highly efficient preparation of enantiomerically pure syn aryl β-hydroxy α-dibenzylamino esters is reported. The outcome was achieved via dynamic kinetic resolution and asymmetric transfer hydrogenation of aryl α-dibenzylamino β-keto esters. The desired products were obtained in high yields (up to 98%) with excellent diastereoselectivity (>20:1 dr) and enantioselectivity (up to >99% ee). Furthermore, this method was applied for the gram-scale preparation of droxidopa.

An efficient and scalable synthesis of eliglustat (1) is herein reported. This novel route features a three-step telescoped process to afford the α-dibenzylamino β-ketoester 6 in 85% overall yield from commercially available 1,4-benzodioxane-6-carboxylic acid 7. The key intermediate 5 was obtained via an efficient ruthenium-catalyzed DKR-ATH reaction, which afforded the desired product in 90% isolated yield with >99:1 dr and 99.7% ee on a 100 g scale. In addition, the amidation of sterically hindered carboxylic acid 14 was optimized and amenable to scale-up. This process not only gives a desirable total yield but also avoids hazardous conditions and chromatographic purification. The robustness of this synthesis was successfully performed on a multigram scale to afford 1 with >99.9% de and >99.9% ee in 56.8% overall yield in nine steps.