the dioxolane ring had a small effect on the asymmetric induction by DIOP in the hydrogenation. Modification at the phosphino group affected the stereocontrol by the ligand and the unsymmetrical DIOP with di-2-naphthylphosphino group gave higher optical yields than (−)-DIOP for the hydrogenation of α-acetamidocinnamic acid and dehydrodipeptides.
A new convenient approach to peptide synthesis using a diselenide and a phosphine
作者:Usha Singh、Sunil K. Ghosh、Mohindra S. Chadha、Vasant R. Mamdapur
DOI:10.1016/0040-4039(91)80869-8
日期:1991.1
A new and highly efficient method based on a redox reaction using diphenyldiselenide and tributylphosphine for the general synthesis of peptides is described. The side reaction due to selenophenol formation is overcome by using chalcone as a scavenger or by selective oxidation to diselenide.
Lithium-Salt Effects in Peptide Synthesis. Part I. Conditions for the Use of Lithium-Salts in Coupling Reactions
作者:Adrian Thaler、Dieter Seebach、Francis Cardinaux
DOI:10.1002/hlca.19910740319
日期:1991.5.2
reactions was investigated. As a model for segment couplings, Ac-Phe-OH was coupled to HCl·H-Ala-OMe using the mixed anhydride, DCC1, DCCl/HOBt, BOP-Castro and TBTU-Knorr methods. As a model for stepwise synthesis Z-Phe-OH was coupled with HCl·Ala-O(t-Bu), using symmetrical anhydrides and active esters. The effects of salt additives such as LiCl, LiBr, LiC104, and ZnCl2 on yields, side-product formation, racemisation
Asymmetric Hydrogenation of Dehydrodipeptides with Rhodium(I)–Chiral Diphosphinites. Selective (<i>S</i>,<i>S</i>)- and (<i>R</i>,<i>R</i>)-Product Formation by Double Asymmetric Induction
stereoselectivities, depending on the chiral center of the substrates. This result was ascribed to the electrostaticinteractionbetween the ligand and substrate. POP’s without ω-(dimethylamino)alkyl group gave (R,R)-product for (R)-substrate in a high stereoselectivity by the steric effect between the ligand and substrate, while for (S)-substrate, (S,S)-product was obtained in a low stereoselectivity.
A concept for the rational design of sequence-selectivepeptide receptors has been extended: in addn. to recognitionmodules for polar, arom. and basic amino acids, the series has now been completed with new receptor units for apolar and acidic amino acids. The underlying strategy uses the intermol. b-sheet stabilization of a dipeptide as a prerequisite to bind its N-terminal amino acid side chain
合理设计序列选择性肽受体的概念已得到扩展:另外。到 polar、arom 的识别模块。和碱性氨基酸,该系列现在已经完成了新的非极性和酸性氨基酸受体单元。底层策略使用 intermol。二肽的 b 片层稳定性,作为通过从受体部分突出的 U 形转弯末端的战略性放置的识别尖端结合其 N 端氨基酸侧链的先决条件。因此,二氨基吡唑已通过环状酰亚胺共价连接到肯普氏三酸,而间位取代的苯胺作为酰胺偶联到第三个羧酸酯悬垂臂上,形成两个芳基。在紧密的构象锁定中将单位转换为子范德华距离。核磁共振滴定,Karplus 分析和蒙特卡洛模拟证明了丙氨酸-contg 的有效序列选择性识别。二肽。以前不存在这样一组合理设计的肽受体的例子。