Synthesis of 3,4,5,6-tetrakisphosphates of DL-1,2-dideoxy-1,2-difluoro-myo-inositol and DL-1,2-dideoxy-1,2-difluoro-scyllo-inositol as analogues of DL-myo-inositol 3,4,5,6-tetrakisphosphate

Abstract

DL-1,2-Dideoxy-1,2-difluoro-myo-inositol was prepared from DL-3,4,5,6-tetra-O-benzyl-myo-inositol in five steps in an overall yield of 36%. The fluoro substituents were introduced with DAST in separate steps by displacement of hydroxy substituents with inversion of stereochemistry. Difluorination could not be achieved in one step because of competing formation of a 1,4-anhydro derivative. DL-1,2-Dideoxy-1,2-difluoro-scyllo-inositol was prepared in 42% overall yield using similar chemistry, with the required inversion of one stereocentre being accomplished by displacement of a tosyl group with caesium propionate. Both difluoroinositol analogues increased the levels of phytic acid (InsP₆) in a skeletal muscle cell line. Each compound was tetraphosphorylated with dibenzyl N,N-diisopropylphosphoramidite in the presence of 1H-tetrazole, with subsequent oxidation of the phosphite with MCPBA. The P–OBn groups were removed by H₂/Pd–C, and the sodium salts of the tetrakisphosphates of the difluoroinositol analogues were obtained by cation exchange.