Novel enediynyl tripeptides 2(aâc) in fully protected forms have been prepared via a sequence of palladium(0)-based Sonogashira coupling. The thermal reactivity of these peptides was shown to be dependent upon the nature of the side chain in the amino acids. Analysis of the CD-spectra of these peptides as well as the variation of chemical shifts with temperature revealed the presence of a β-sheet nucleating conformation in equilibrium with a conformation induced by H-bond formation between the CO and NH belonging to the enediynyl amino acid.
通过一系列基于钯(0)的 Sonogashira 偶联反应,制备出了完全受保护的新型烯二炔基三肽 2(aâc)。研究表明,这些肽的热反应性取决于氨基酸侧链的性质。对这些肽的 CD 光谱以及化学位移随温度变化的分析表明,烯二炔基氨基酸的 CO 和 NH 之间形成的 H 键诱导了δ-片状核构象与δ-片状核构象的平衡。
DNA-Cleavage studies on N-substituted monocyclic enediynes: enhancement of potency by incorporation of intercalating or electron poor aromatic ring and subsequent design of a novel phototriggerable acyclic enediyne
作者:Amit Basak、Hussam Moh'd Bdour、Jagadish Chandra Shain、Subrata Mandal、Kakali Rani Rudra、Sikha Nag
DOI:10.1016/s0960-894x(00)00237-7
日期:2000.6
N-substituted enediynes (azaenediynes) 1-4 were synthesized as DNAcleaving agents. Enhancement of DNA cleavage potency was observed with those compounds which could interact with DNA through intercalation of the extended aromatic ring or through electrostatic attraction with electron poor aromatic ring. An acyclic enediyne 5 with a novel phototriggerable device was also synthesized and its DNA-cleaving
A number of N-substituted cyclic enediynes (azaenediynes) have been synthesized via Pd(0)-catalysed ene–yne coupling followed by N-alkylation. The simplest of them, a 10-membered monocyclic enediyne 1, underwent Bergman cyclization (BC) at 23 °C with a half-life of 72 h. The kinetics of BC slowed down considerably by fusing a benzene ring onto the enediyne. Several novel bis(azaenediyne)s and bis(diazaenediyne)s 3–6 have been synthesized. Their onset temperatures for BC were lowered under metal ion complexation conditions.