Tofogliflozin (hydrate)

Tofogliflozin hydrate, which is a sodium-glucose co-transporter 2 inhibitor, was approved in Japan for the treatment of type 2 diabetes at the same time as luseogliflozin hydrate (XIX). The drug was discovered by Chugai Pharmaceutical and jointly developed with Sanofi-Aventis and Kowa. Tofogliflozin hydrate reduces glucose levels by inhibiting the reuptake of glucose by selectively inhibiting SGLT2, and plays a key role in the reuptake of glucose in the proximal tubule of the kidneys.

Tofogliflozin hydrate (CSG-452 hydrate) is a potent and highly specific sodium/glucose cotransporter 2 (SGLT2) inhibitor with an IC50 of 2.9 nM and Ki values of 2.9 nM, 14.9 nM, and 6.4 nM for human, rat, and mouse SGLT2[1]. Tofogliflozin partially inhibits high glucose-induced reactive oxyen species (ROS) generation in tubular cells[2].

Reduction of commercially available 2-bromoterephtalic acid (268) through the use of trimethoxyborane and borane- THF proceeded in 89% yield to afford diol 269. Subjection of this compound to 2-methoxypropene (270) under acidic conditions generated bis-acetonide 271. This bromide then underwent lithium¨Chalogen exchange followed by exposure to magnesium bromide and treatment with lactone 272 (which was prepared by persilylation of commercially available (3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2Hpyran- 2-one (277). This mixture was worked up with aqueous ammonium chloride and upon treatment with p-TsOH in methanol resulted in spiroacetal 273. Next, global protection of all alcohol functionalities within 273 was affected by reaction with methylchloroformate and DMAP in acetonitrile. The benzyl carbonate within 274 was selectively exchanged via Suzuki coupling with 4-ethylphenylboronic acid (275) to afford methylene dibenzyl system 276. Subsequent treatment with aqueous sodium hydroxide in methanol followed by crystallization from 1:6 acetone and water furnished the desired product tofogliflozin hydrate (XXXIV) in 75% yield.

SGLT2

[1] Suzuki M, et al. Tofogliflozin, a potent and highly specific sodium/glucose cotransporter 2 inhibitor, improves glycemic control in diabetic rats and mice. J Pharmacol Exp Ther. 2012 Jun;341(3):692-701. DOI:10.1124/jpet.112.191593
[2] Ishibashi Y, et al. Tofogliflozin, A Highly Selective Inhibitor of SGLT2 Blocks Proinflammatory and Proapoptotic Effects of Glucose Overload on Proximal Tubular Cells Partly by Suppressing Oxidative Stress Generation. Horm Metab Res. 2016 Mar;48(3):191-5. DOI:10.1055/s-0035-1555791