Langenhan Joseph M, Gellman Samuel H
Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396, USA.
J Org Chem. 2003 Aug 8;68(16):6440-3. doi: 10.1021/jo034583h.
We report the synthesis of syn-alpha,beta-dialkyl beta-amino acid derivatives suitably protected for solid-phase synthesis that give rise to residues containing positively charged lysine-like side chains. These amino acids, as well as syn-alpha,beta-dialkyl beta-amino acids that contain diverse hydrophobic side chains, are prepared in good de and ee. The key step in this route involves Davies's protocol for the conjugate addition of a chiral lithium amide to alpha,beta-unsaturated tert-butyl esters (Davies, S. G.; Ichihara, O.; Walters, I. A. S. J. Chem. Soc., Perkin Trans. 1 1994, 9, 1141). syn-alpha,beta-Dialkyl beta-amino acids are interesting building blocks because of their sheet-forming propensity and because of their presence in bioactive compounds.
我们报道了经适当保护用于固相合成的顺式α,β-二烷基β-氨基酸衍生物的合成，这些衍生物可产生含有带正电荷的赖氨酸样侧链的残基。这些氨基酸以及含有各种疏水侧链的顺式α,β-二烷基β-氨基酸，以良好的非对映体过量和对映体过量制备。该路线中的关键步骤涉及戴维斯的手性锂酰胺与α,β-不饱和叔丁酯共轭加成的方法（戴维斯，S.G.；市原，O.；沃尔特斯，I.A.S.《化学会志，珀金 Transactions 1》1994年，9，1141）。顺式α,β-二烷基β-氨基酸是有趣的结构单元，因为它们具有形成片层的倾向，并且存在于生物活性化合物中。
