Biosynthesis of natural products with a phosphorus-carbon bond. 7. Synthesis of [1,1-2H2]-, [2,2-2H2]-, (R)- and (S)-[1-2H1](2-hydroxyethyl)phosphonic acid and (R,S)-[1-2H1](1,2-dihydroxyethyl)phosphonic acid and incorporation studies into fosfomycin in Streptomyces fradiae