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Isotopically labeled compounds have numerous applications in drug discovery and development. (R)-9-(2-Hydroxypropyl)adenine 1 is an important intermediate in the synthesis of various acyclic nucleoside phosphonates including tenofovir. We have developed a short synthetic method to prepare deuterium and tritium labeled 1 using a ketoreductase enzyme catalyzed reduction as the key step to introduce the label in a highly efficient and enantioselective way.

Process development of the synthesis of the orally active poly(ADP-ribose)polymerase inhibitor niraparib is described. Two new asymmetric routes are reported, which converge on a high-yielding, regioselective, copper-catalyzed N-arylation of an indazole derivative as the late-stage fragment coupling step. Novel transaminase-mediated dynamic kinetic resolutions of racemic aldehyde surrogates provided enantioselective syntheses of the 3-aryl-piperidine coupling partner. Conversion of the C–N cross-coupling product to the final API was achieved by deprotection and salt metathesis to isolate the desired crystalline salt form.

A practical preparation of an αvβ3 antagonist is reported. The antagonist consists of three key components, a tetrahydronaphthyridine moiety, a β-alanine moiety, and a central imidazolidone moiety. The tetrahydronaphthyridine component was prepared using two different methods, both of which relied on variations of the Friedlander reaction to establish the desired regiochemistry. The β-alanine component was prepared using Davies' asymmetric 1,4-addition methodology as the key stereo-defining step. The central imidazolidone portion was created from these two components using an effective three-step cyclization protocol. Thus, a highly convergent process for the drug candidate was defined.

2-Amino-3-pyridinecarboxaldehyde is synthesized in a highly efficient process via ortho-lithiation of 2-(pivaloylamino)pyridine and reaction with DMF, followed by acid hydrolysis. Major impurities were identified and were cleanly eliminated through careful choice of base and solvent.

[reaction: see text]. A highly regioselective Friedländer reaction is described. By introduction of a phosphonate group at one of the alpha-carbons of a ketone, regioselectivity can be perfectly controlled.

A highly efficient synthesis of sitagliptin, a potent and selective DPP-4 inhibitor for the treatment of type 2 diabetes mellitus (T2DM), has been developed. The key dehydrositagliptin intermediate 9 is prepared in three steps in one pot and directly isolated in 82% yield and >99.6 wt % purity. Highly enantioselective hydrogenation of dehydrositagliptin 9, with as low as 0.15 mol % of Rh(I)/tBu JOSIPHOS, affords sitagliptin, which is finally isolated as its phosphate salt with nearly perfect optical and chemical purity. This environmentally friendly, ‘green’ synthesis significantly reduces the total waste generated per kilogram of sitagliptin produced in comparison with the first-generation route and completely eliminates aqueous waste streams. The efficiency of this cost-effective process, which has been implemented on manufacturing scale, results in up to 65% overall isolated yield.

A direct asymmetric hydrogenation of unprotected enamino esters and amides is described. Catalyzed by Rh complexes with Josiphos-type chiral ligands, this method gives beta-amino esters and amides in high yield and high ee (93-97% ee). No acyl protection/deprotection is required.

Pure (Z)-enamines readily prepared from beta-ketoesters and amides using (S)-phenylglycine amide were hydrogenated with very high diastereoselectivities (up to 200:1) using heterogeneous catalysis. Hydrogenolytic cleavage of the (S)-phenylglycine amide afforded the corresponding chiral beta-aminoesters and amides. The high geometrical purity of the (Z)-enamine and a simple activation procedure for the PtO2 catalyst are essential in achieving high selectivity.