Bioactive Pseudopeptidic Analogues and Cyclostereoisomers of Osteogenic Growth Peptide C-Terminal Pentapeptide, OGP(10−14)
摘要:
The osteogenic growth peptide (OGP) is a key factor in the mechanism of the systemic osteogenic response to local bone marrow injury. When administered an vivo, OGP stimulates osteogenesis and hematopoiesis. The C-terminal pentapeptide OGP(10-14) is the minimal amino acid sequence that retains the full OGP-like activity. Apparently, it is also the physiologic active form of OGP. Residues Tyr(10), Phe(12), Gly(13), and Gly(14) of OGP are essential for the OGP(10-14) activity. The present study explored the functional role of the peptide bonds, carboxyl and amino terminal groups, and conformational freedom in OGP(10-14). Transformations replacing the peptide bonds with surrogates such as Psi(CH2Me), Psi(CONMe), and Psi(CH2CH2) demonstrated that amide bonds do not contribute significantly to OGP(10-14) bioactivity. End-to-end cyclization yielded the fully bioactive cyclic pentapeptide c(Tyr-Gly-Phe-Gly-Gly). The retroinverso analogue c(Gly-Gly phe-Gly-tyr), a cyclostereoisomer of c(Tyr-Gly-Phe-Gly-Gly), is at least as potent as the parent cyclic pentapeptide. The unique structure-activity relations revealed in this study suggest that the spatial presentation of the Tyr and Phe side chains has a major role in the productive interaction of OGP(10-14) and its truncated and conformationally constrained analogues with their cognate cellular target.
One-Pot, Enantioselective Synthesis of 2,3-Dihydroazulen-6(1<i>H</i>)-one: A Concise Access to the Core Structure of<i>Cephalotaxus</i>Norditerpenes
作者:Yongsheng Zheng、Ebrahim H. Ghazvini Zadeh、Yu Yuan
DOI:10.1002/ejoc.201600321
日期:2016.4
A one-pot enantioselective synthesis of cis-substituted 2,3-dihydroazulen-6(1H)-one is described. In this cascade reaction, an organocatalyzed asymmetricMichaelreaction furnishes a highly optically pure nitrobutylphenol intermediate, which is converted into an annulated tropone species by sequential oxidative dearomatization, conjugate addition, electrocyclic ring opening and nitrous acid elimination
An oxidative dearomatization of phenol followed by a dynamic kinetic (DyKat) ketalization/oxa-Michael addition cascade using cinchona alkaloid-based chiral bifunctional amino-squaramide catalysts is reported. A broad array of sterically hindered [5,5]-spiroketals attached to a cyclohexadienone moiety in spiro-fashion is synthesized in an enantiopure form. Further, the methodology was optimized and
Divergent reactivity of phenol- and anisole-tethered donor-acceptor α-diazoketones
作者:Aimee K. Clarke、William P. Unsworth、Richard J.K. Taylor
DOI:10.1016/j.tet.2018.02.003
日期:2018.9
The first study of the divergent reactivity of phenol/anisole-tethered donor-acceptor α-diazoketones is described. Four distinct product classes were shown to be accessible from closely related α-diazoketone precursors, with the reaction outcome dependent on the nature of the oxygen substituent on the phenol/anisole ring and the catalyst used to decompose the diazo group. Anisole and TBS-protected
An Oxidative Prins-Pinacol Tandem Process and its Application to the synthesis of (−)-Platensimycin
作者:Marc-André Beaulieu、Cyrille Sabot、Nabil Achache、Kimiaka C. Guérard、Sylvain Canesi
DOI:10.1002/chem.201001813
日期:——
Center stage: An oxidative Prins–pinacol tandemprocess mediated by a hypervalent iodine reagent has been accomplished. The strategy allows rapid access to highly functionalized spirocyclic cores (see scheme) present in many natural products. A first application to the formal synthesis of (−)‐platensimycin has been achieved.