Dioxabicyclooctanyl Naphthalenenitriles as Nonredox 5-Lipoxygenase Inhibitors: Structure−Activity Relationship Study Directed toward the Improvement of Metabolic Stability
摘要:
Naphthalenic lignan lactone 3a (L-702,539), a potent and selective 5-lipoxygenase (5-LO) inhibitor, is extensively metabolized at two different sites: the tetrahydropyran and the lactone rings. Early knowledge of the metabolic pathways triggered and directed a structure-activity relationship study aimed toward the improvement of metabolic stability in this series. The best modifications discovered, i.e., replacement of the lactone ring by a nitrile group, replacement of the tetrahydropyran ring by a 6,8-dioxabicydo[3.2.1]octanyl moiety, and replacement of the pendant phenyl ring by a 3-furyl ring, were incorporated in a single molecule to produce inhibitor 9ac (L-708,780). Compound 9ac inhibits the oxidation of arachidonic acid to 5-hydroperoxy-eicosatetraenoic acid by 5-LO (IC50 = 190 nM) and the formation of leukotriene B-4 in human polymorphonuclear leukocytes (IC50 = 3 nM) as well as in human whole blood (IC50 = 150 nM). The good inhibitory profile shown by naphthalenenitrile 9ac is accompanied by an improved resistance to oxidative metabolism. In addition, 9ac is orally active in the functional model of antigen-induced bronchoconstriction in allergic squirrel monkeys (95% inhibition at 0.1 mg/kg).
General conjugate-addition method for the synthesis of enantiomerically pure lignans. Total synthesis of (-)- and (+)-burseran, (-)-dehydroxycubebin, (-)-trichostin, (-)-cubebin, (-)-5''-methoxyhinokinin, and (-)-hinokinin
A Transition-Metal-Free and Base-Mediated Carbene Insertion into Sulfur-Sulfur and Selenium-Selenium Bonds: An Easy Access to Thio- and Selenoacetals
作者:Dhanarajan Arunprasath、Govindasamy Sekar
DOI:10.1002/adsc.201600855
日期:2017.2.20
A transition‐metal‐free and base‐mediated carbene insertion across sulfur‐sulfur and selenium‐selenium bonds has been developed by employing N‐tosylhydrazone as a stable and safe carbene precursor. The ylide formation from carbene followed by Stevens rearrangement are considered to be the key steps. This thiol and selenol‐free protocol delivers thioacetals and selenoacetals in good to excellent yields