Pentacovalent phosphorus in organic synthesis: A new route to substituted phosphonates

WCC 19

Danielle Marie Stacy, dms009@truman.edu, Department of Chemistry, Truman State University, Science Division, 100 E Normal, Kirksville, MO 63501 and Cynthia K. McClure, cmcclure@chemistry.montana.edu, Department of Chemistry and Biochemistry, Montana State University, 108 Gaines Hall, Bozeman, MT 59717.
Common to all living systems are phosphate containing compounds such as phospholipids, carbohydrates, nucleic acids, and proteins. These compounds play key roles in metabolic processes, such as signal transduction, calcium regulation, and even cell proliferation. Altering the chemistry of these organophosphorus compounds by substituting the phosphate group for a phosphonate, which has a carbon-phosphorus bond in place of the P-O of the phosphate, increases the bond strength of the linkage, and inhibits the molecule from participating in a vast array of normal metabolic processes.

In this synthetic route, 2,2-dimethyloxazolidine-(4R)-3,4-dicarboxylic acid 3-tert-butyl ester 4-methyl ester (Garner's ester) was reduced to (4S)-4-hydroxymethyl-2,2-dimethyloxazolidine-3-carboxylic acid tert-butyl ester (Garner's alcohol) and then oxidized to (4R)-4-formyl-2,2-dimethyloxazolidine-3-carboxylic acid tert-butyl ester (Garner's aldehyde). The aldehyde then participated in an electrophilic condensation with a pentacovalent oxaphospholene. The final product of this synthesis can be used to make a cyclic structure similar to that of a known inhibitor of N and O-glucosidases, with the advantage of containing a stronger phosphorus-carbon bond.