F-butoxy carbonyl

A wide choice of peptide synthesizers is currently available, ranging from manual to fully automated. They are all based on solid-phase peptide synthesis methodologies in which either f-butoxy carbonyl (t-boc) (11), or 9-fluor-enylmethoxycarbonyl (Fmoc) (12) is the major protecting group during synthesis. A detailed description of peptide synthesis is clearly beyond the scope of this chapter, and further information on practical and theoretical approaches to this chemistry may be found elsewhere (13-15). However, a brief outline of solid-phase synthesis may prove useful. 

Substitution at the terminal position of the aUylstannane, as in crotonyltributyl stannane, however, is not tolerated, because hydrogen abstraction from the allylic position is a competing reaction [21]. An extension of the method involves the coupling of the anomeric radical precursors 28 with the allyltributyltin reagent 29 [14]. In the reagent 29 the double bond is activated toward addition of nucleophilic radicals by the electron-withdrawing f-butoxy carbonyl group. The obtained product 30 has been useful en route to 3-deoxy-D-man/io-2-octulosonic acid (KDO). 

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