Total synthesis and structural revision of engelhardione
作者:Li Shen、Dianqing Sun
DOI:10.1016/j.tetlet.2011.06.112
日期:2011.8
The total synthesis of the macrocyclic natural product engelhardione is reported. This effort led to the structural revision of the published structure of engelhardione to that of pterocarine. The revision reflects the change of the substitution pattern of one phenyl ether ring from the meta to the para position. To confirm, pterocarine (2) and its close regioisomer 3 were subsequently synthesized
Syntheses and evaluation of macrocyclic engelhardione analogs as antitubercular and antibacterial agents
作者:Li Shen、Marcus M Maddox、Sudip Adhikari、David F Bruhn、Manish Kumar、Robin E Lee、Julian G Hurdle、Richard E Lee、Dianqing Sun
DOI:10.1038/ja.2013.21
日期:2013.6
The natural product engelhardione is an underexplored chemotype for developing novel treatments for bacterial infections; we therefore explored this natural product scaffold for chemical diversification and structureâactivity relationship studies. Macrocyclic engelhardione and structural regioisomers were synthesized using a series of aldol condensations and selective hydrogenations to generate the 1,7-diarylheptan-3-one derivatives, followed by microwave-assisted intramolecular Ullmann coupling to afford a series of macrocyclic diaryl ether analogs. An extended macrocyclic chemical library was then produced by oxime formation, reductive amination and O-alkylation. Antibacterial evaluation revealed that the reductive amination derivatives 7b and 7d showed moderate activities (minimum inhibitory concentrations: 12.5â25âμgâmlâ1) against Mycobacterium tuberculosis and Gram-positive pathogens, as well as anti-Gram-negative activity against an efflux impaired Escherichia coli strain. These results provide validated leads for further optimization and development.
Bio-inspired oxidative phenolic coupling: Total synthesis of the diarylether heptanoid (±)-pterocarine
作者:M. Quamar Salih、Christopher M. Beaudry
DOI:10.1016/j.tetlet.2017.04.015
日期:2017.5
pterocarine, is expeditiously synthesized using a bioinspired intramolecular oxidativephenoliccoupling of acerogenin G. The cyclization precursor is prepared from a simple cinnamic acid derivative in three high yielding synthetic operations. The key oxidativecoupling is inspired by biosynthetic hypotheses; however, the oxidativecoupling proceeds with concomitant hydroxylation of the diphenyl ether motif