A new type of amino-protecting group is described in which a Michael acceptor is incorporated into the protectant so that treatment with a nucleophile will trigger deblocking. Comparison of various Michael acceptors showed that for several key electron-withdrawing groups, the order of reactivity was C 6 H 5 SO 2 > Me 3 CSO 2 > COOEt > C 6 H 5 SO > C 6 H 4 NO 2 -p. The reactivity of the nucleophile (e.g., primary and secondary aliphatic amines) followed an order related to both intrinsic basicity and steric effects. β-Substituents in the Michael acceptor caused significant retardation of the deblocking process. The Bspoc function was chosen for initial elaboration into a practical system for use in peptide synthesis. Bspoc amino acid chlorides were used as coupling agents and silicatethered secondary amines as deblocking agents. With the latter, deblocking occurs cleanly and no byproducts remain in the organic solvent in which the deblocking is executed.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.