Stereoselective lodocyclization of (S)-allylalanine derivatives: γ-lactone vs cyclic carbamate formation
An efficient procedure for highly chemo- and stereoselective cyclization of (S)-allylalanine derivatives is reported (diastereomeric ratios up to 96:4) where the reaction course can be completely controlled by switching from γ-lactones to cyclic carbamate
Synthesis of enantiopure functionalized pipecolic acids via amino acid derived N-acyliminium ions
The synthesis and enzymatic resolution of a novel vinylsilane-containing amino acid is described. Derivatization of this and other olefinic amino acids followed by subjection to standard N-acyliminium ion cyclization conditions provides the corresponding pipecolic acid derivatives with - in most cases - complete conservation of enantiopurity. In addition to studying the scope of this reaction, details of the N-acyliminium ion cyclization including an aza Cope equilibrium are highlighted.
Rutjes, Floris P. J. T.,Veerman, Johan J. N.,Meester, Wim J. N.,Hiemstra, Henk,Schoemaker, Hans E.
p. 1127 - 1135
(2007/10/03)
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