The yield of protected 2,7- diaminosuberic acid (DAS) prepared by Kolbe reaction of N-protected α-glutamic acid esters is dependent on solvent, temperature, concentration of carboxylate anion, and protecting groups. The highest yield of protected L,L-2,7-diaminosuberic acid is obtained with Boc-Glu-OMe as starting material using MeOH/pyridine/NaOMe as electrolyte.
simple and efficient method for the synthesis of dehydroamino acidsfromserine and threonine is reported. Various O-Cbz and O-Eoc derivatives of serine and threonine are prepared using CbzCl and EocCl, respectively, and are subjected to an anti-selective elimination on treatment with K2CO3 in DMF at 65 °C to afford dehydroalanine and dehydroamino butyric acidderivatives, respectively, in excellent yields
据报道,一种简单有效的从丝氨酸和苏氨酸合成脱氢氨基酸的方法。各种Ò -Cbz和ö丝氨酸-Eoc衍生物和苏氨酸分别使用CbzCl和EocCl,制备,并且经受抗-选择性消除治疗以K 2 CO 3在DMF中在65℃下,得到脱氢丙氨酸和脱氢丁酸酸衍生物,分别具有优异的收率。这些丝氨酸和苏氨酸的碳酸盐衍生物的高稳定性使得它们可以作为受保护的丝氨酸和苏氨酸残基用于正常的肽合成中。通过掺入O -Cbz或O合成的肽-Eoc衍生物在所报道的条件下容易消除,从而以极好的收率得到相应的脱氢肽。反应条件足够温和,不会引起肽中存在的其他立体异构中心的外消旋化。
An improved procedure for the synthesis of dehydroamino acids and dehydropeptides from the carbonate derivatives of serine and threonine using tetrabutylammonium fluoride
E2 elimination of the carbonate derivatives of serine and threonine using TBAF is milder and more efficient than other available procedures. The elimination reaction is completed in less than 10 min with various carbonate derivatives studied and the methodology is very efficient for the synthesis of dehydroamino acids and dehydropeptides. The procedure thus provides an easy access to key synthetic precursors
Silver-Promoted Direct Phosphorylation of Bulky C(sp<sup>2</sup>)–H Bond to Build Fully Substituted β-Phosphonodehydroamino Acids
作者:Hao-Qiang Cao、Hao-Nan Liu、Zhe-Yuan Liu、Baokun Qiao、Fa-Guang Zhang、Jun-An Ma
DOI:10.1021/acs.orglett.0c02229
日期:2020.8.21
A general and practical cross-dehydrogenative coupling protocol between readily available trisubstituted α,β-dehydro α-amino carboxylic esters and H-phosphites is described. This C(sp2)–H phosphorylation reaction proceeds with absolute Z-selectivity promoted by silver salt in a radical relay manner. The bulky tetrasubstituted β-phosphonodehydroamino acids were obtained in grams and added new modules