A novel and highly diastereoselective intramolecular carbamoylketene/alkene [2 + 2] cycloaddition has been developed, and the methodology was successfully applied to the enantioselective syntheses of (−)-esermethole and Takayama’s intermediate for (+)-psychotrimine.
Asymmetric Synthesis of Dihydropyranones via Gold(I)‐Catalyzed Intermolecular [4+2] Annulation of Propiolates and Alkenes
作者:Hanbyul Kim、Su Yeon Choi、Seunghoon Shin
DOI:10.1002/anie.201807514
日期:2018.10
Intermolecular asymmetric gold catalysis involving alkyne activation presents a significant challenge due to its distinct mechanistic mode from other metals. Herein, we report a highly enantioselective synthesis of α,β‐unsaturated δ‐lactones from [4+2] annulation of propiolates and alkenes in upto 95 % ee. Notably, for the desired chiral recognition, the choice of 1,1,2,2‐tetrachloroethane as solvent
Stereodefined alkenes with a fluoro-chloro terminus as a uniquely enabling compound class
作者:Qinghe Liu、Yucheng Mu、Tobias Koengeter、Richard R. Schrock、Amir H. Hoveyda
DOI:10.1038/s41557-022-00893-5
日期:2022.4
Trisubstituted alkenyl fluorides are important compounds for drug discovery, agrochemical development and materials science. Despite notable progress, however, many stereochemically defined trisubstituted fluoroalkenes either cannot be prepared efficiently or can only be accessed in one isomeric form. Here we outline a general solution to this problem by first unveiling a practical, widely applicable
Synthesis of Sulfur- and Sulfoxide-Substituted 2,3-Oxidosqualenes and Their Evaluation as Inhibitors of 2,3-Oxidosqualene-Lanosterol Cyclase
作者:Yi Feng Zheng、Allan C. Oehlschlager、Nafsika H. Georgopapadakou、Peter G. Hartman、Petra Scheliga
DOI:10.1021/ja00107a011
日期:1995.1
2,3-Oxidosqualene (23-OS) analogs that contain thioether (52-55) and sulfoxide (56-60) at positions normally occupied by carbons considered to be cationic during 2,3-oxidosqualene-lanosterol cyclase (OSC) cyclization (C-6, C-10, C-14, and C-19) were synthesized and tested as substrate mimic inhibitors of fungal and mammalian OSC. The analogs were found to be potent inhibitors of cyclase in cell-free extracts of Candida albicans and rat liver. Thioether analogs were more potent than the corresponding sulfoxides. In both series, those 2,3-OS analogs containing a sulfur at the position normally occupied by C-19 were the most potent. With C. albicans cyclase, the IC50 for thioether 55 was 0.0023 mu M while 60 exhibited an IC50 of 0.065 mu M, which are the lowest values reported for a inhibitor of this enzyme. Similarly, thioether 55 displayed an IC50 of 0.00082 mu M for rat liver cyclase which is the best inhibitor up to date for this enzyme. These results suggest that mimics with modification in the region of C-19 of 2,3-OS have a high affinity for the active site of these enzymes. The same series of analogs (52-60) were also tested for inhibition of cholesterol biosynthesis in intact MDBK (Madin Darbin bovine kidney) cells and for in vitro antifungal activity against C. albicans.