Preclamol

Piperidines are frequently found in natural products and are of importance to the pharmaceutical industry. A generally useful asymmetric route to enantiomerically enriched 3-substituted piperidines remains elusive. Here we report a cross-coupling approach to enantioenriched 3-piperidines from pyridine- and sp²-hybridized boronic acids. The key step involves a Rh-catalyzed asymmetric reductive Heck reaction of aryl, heteroaryl, or vinyl boronic acids and phenyl pyridine-1(2H)-carboxylate to provide 3-substituted tetrahydropyridines in high yield and excellent enantioselectivity with a wide functional group tolerance. A three-step process involving i) partial reduction of pyridine, ii) Rh-catalyzed asymmetric carbometalation, and then iii) another reduction provides access to a wide variety of enantioenriched 3-piperidines, including clinically used materials such as Preclamol and Niraparib.

Sulfotransferases (STs) are ubiquitous enzymes that participate in a vast number of biological processes involving sulfuryl group (SO₃) transfer. 3'-phosphoadenosine 5'-phosphosulfate (PAPS) is the universal ST cofactor, serving as the "active sulfate" source in cells. Herein, we report the synthesis of three fluorinated PAPS analogues that bear fluorine or trifluoromethyl substituents at the C2 or C8 positions of adenine and their evaluation as substitute cofactors that enable ST activity to be quantified and real-time-monitored by fluorine-19 nuclear magnetic resonance (¹⁹F NMR) spectroscopy. Using plant AtSOT18 and human SULT1A3 as two model enzymes, we reveal that the fluorinated PAPS analogues show complementary properties with regard to recognition by enzymes and the working ¹⁹F NMR pH range and are attractive versatile tools for studying STs. Finally, we developed an ¹⁹F NMR assay for screening potential inhibitors against SULT1A3, thereby highlighting the possible use of fluorinated PAPS analogues for the discovery of drugs for ST-related diseases.