Barton glutamate

Najlerahim A, Harrison PJ, Barton AJL, Heffernan J, Pearson RCA (1990) Distribution of messenger RNAs encoding the enzymes glutaminase, aspartate aminotransferase and glutamic acid decarboxyla.se in rat brain. Mol Brain Res 7 317-333. 

White phosphorus in THF reacts in a long radical chain reaction with carbon radicals derived from Barton s PTOC esters. Oxidation of the adducts (HgOg or SOg) provides a convenient synthesis of phosphonic acids. For sensitive products the further transformation to phosphonic acids is best carried out with an excess of SO2. The reaction is illustrated by the synthesis of L-2-amino-4-phosphonobutyric acid in 58% yield from L-glutamic acid using the appropriate protecting groups (Scheme 8.91). ... 

Side-chain halogenated amino acid derivatives are reduced, deuterated, allylated and alkylated with stannanes and related reagents in free-radical processes [53]. Other side-chain functional groups may also be manipulated to produce amino acid radicals [8, 54-58], and, in particular. Barton decarboxylation of aspartate and glutamate derivatives has been applied in this manner (Scheme 8) [55]. Related procedures have been developed to generate amino acid radicals by dehydrox-ylation of hydroxy amino acid derivatives [56]. Hydroxy amino acid derivatives may also be converted to nitrate esters, from which the corresponding alkoxy radi-... 

Self-catalyzed transesterification with 2-dimethylaminoethanol in DMF has been found effective in cleaving protected peptides from the Mer-rifield resin, in the absence of side-chain benzyl ester protecting groups (Barton et al., 1973). This mild, virtually racemization-free procedure may prove extremely useful for fragment condensation because it yields N-Z-and iV-Boc-protected peptides. Since the reagent, 2-dimethyl-amino-ethanol, specifically cleaves of the benzylic ester group, the benzyl esters of glutamic acid and aspartic acid, if present, will also be hydrolyzed (Barton et al., 1973 Savoie and Barton, 1974). 

---