The phosphonic acid derivatives (4-oxo-4H-chromen-3-yl) hydroxymethyl) phosphonic acid or (4-oxo-4H-chromen-3-yl) -methyl) acid.

摘要

Compounds of formula I ** ** Formula wherein R1 to R3 are each, independently of one another, H, hydroxy or alkoxy having 1 to 8 carbon atoms, R4 is alkyl having 1 to 4 carbon atoms, H , hydroxy or alkoxy having 1 to 8 carbon atoms, R5 is H or hydroxy and R6 is H or alkyl having 1 to 18 carbon atoms or salts thereof, without, however, all radicals R1 to R4 together can be equal to H.