Synthesis of Cyclic Pyranopterin Monophosphate, a Biosynthetic Intermediate in the Molybdenum Cofactor Pathway

Abstract

Cyclic pyranopterin monophosphate (1), isolated from bacterial culture, has previously been shown to be effective in restoring normal function of molybdenum enzymes in molybdenum cofactor (MoCo)-deficient mice and human patients. Described here is a synthesis of 1 hydrobromide (1·HBr) employing in the key step a Viscontini reaction between 2,5,6-triamino-3,4-dihydropyrimidin-4-one dihydrochloride and D-galactose phenylhydrazone to give the pyranopterin (5aS,6R,7R,8R,9aR)-2-amino-6,7-dihydroxy-8-(hydroxymethyl)-3H,4H,5H,5aH,6H,7H,8H,9aH,10H-pyrano[3,2-g]pteridin-4-one (10) and establishing all four stereocenters found in 1. Compound 10, characterized spectroscopically and by X-ray crystallography, was transformed through a selectively protected tri-tert-butoxycarbonylamino intermediate into a highly crystalline tetracyclic phosphate ester (15). The latter underwent a Swern oxidation and then deprotection to give 1·HBr. Synthesized 1·HBr had in vitro efficacy comparable to that of 1 of bacterial origin as demonstrated by its enzymatic conversion into mature MoCo and subsequent reconstitution of MoCo-free human sulfite oxidase-molybdenum domain yielding a fully active enzyme. The described synthesis has the potential for scale up.

The Mononuclear Molybdenum Enzymes

“…16 An efficient total synthesis of cPMP has recently been reported that yields material that can be enzymatically converted to mature cofactor capable of reconstituting apo sulfite oxidase. 17 …”

Molybdenum in Human Health and Disease

“…Depending on the time of treatment initiation, patients can reach an almost normal neurodevelopmental outcome [ 165 ]. Very recently, the chemical synthesis of cPMP has been reported, providing a key milestone in the clinical development of cPMP therapy [ 166 ].…”

Storage of Potassium Ions in Layered Vanadium Pentoxide Nanofiber Electrodes for Aqueous Pseudocapacitors

“…The cPMP ( 2 ) necessary is currently being produced biotechnologically, using genetically modified E. coli developed by Schwarz et al,6,11b,13b,14a followed by HPLC purification, and storage at –80 °C 11b. Recently, the organic synthesis of labile cPMP ( 2 ) using the Viscontini reaction as the key step was reported 14b,14c…”