The role of 5-methy 1-FH4 in biology is to serve as a donor of methyl groups to small molecules. The synthesis of the amino acid methionine from homocysteine is perhaps the best-known example.

For this problem, answer the same questions that were posed in Problem 69. The pKα of the circled hydrogen in FH4 is 5. Does this cause a problem with any feature of your mechanism? In fact, methyl transfer reactions of 5-methyl-FH4 require a proton source. Review the material in Section 9-2, especially the subsection titled "Haloalkanes from primary alcohols and HX." Then suggest a useful role for a proton in the reaction illustrated here?

Transcribed Image Text:

NH2 NH2 CH2NHHOC HOC CH3 5-Methyl-FH Methionine Homocysteine FH