Asymmetric Total Synthesis of (−)-Spirochensilide A, Part 1: Diastereoselective Synthesis of the ABCD Ring and Stereoselective Total Synthesis of 13(<i>R</i>)-Demethyl Spirochensilide A
construction of the ABCD ring system of spirochensilide A is described. The key steps of this synthesis are a semipinacol rearrangement reaction to stereoselectively construct the AB ring system bearing two vicinal quaternary chiral centers and a Co-mediated Pauson–Khand reaction to form the spiro-based bicyclic CD ring system. This chemistry leads to the stereoselective synthesis of 13(R)-demethyl spirochensilide
Novel quinuclidine-based ligands for the muscarinic cholinergic receptor
作者:John Saunders、Mark Cassidy、Stephen B. Freedman、Elizabeth A. Harley、Leslie L. Iversen、Clare Kneen、Angus M. MacLeod、Kevin J. Merchant、Roger J. Snow、Raymond Baker
DOI:10.1021/jm00166a008
日期:1990.4
been discovered that an oxadiazole ring and related heterocycles can function as bioisosteric replacements for the ester moiety found in several known muscarinic ligands. Within this series there exist compounds which span the efficacy range from high-efficacy agonist through partial agonists to antagonists with affinity comparable or superior to that of classical quaternary ammonium ligands. Consistent
Reactions of ethyl diazoacetate with β-methylfurans
作者:Ernest Wenkert、Haripada Khatuya、Phillip S. Klein
DOI:10.1016/s0040-4039(99)01007-2
日期:1999.7
Reactions of β-methylfuran and 2,4-dimethylfuran with ethyldiazoacetate in the presence of [Rh2(OAc)4] catalyst, followed by iodine-induced isomerization, yielded furan ring-unravelled products. The results are compared with those of α-methylfurans.
Enantioselective synthesis of (–)-malyngolide (1) was accomplished by employing diastereo-selective addition of nonylmagnesium bromide to the 2-acylfuran derivative (4), followed by a ring transformation of the resulting optically active 2-furylalcohol (5) to give the pyranone derivative (7) as key steps.
General routes to 4-methyl-2-substituted-furans: a total synthesis of pleraplysillin-2, a metabolite of the sponge, Pleraplysilla spinifera
作者:David W. Knight、David C. Rustidge
DOI:10.1039/p19810000679
日期:——
A general approach to 4-methyl-2-substituted-furans is described in which 4-methyl-2-furyl-lithium is the key intermediate. Using this method, pleraplysillin-2, a sesquiterpenoid ester from the sponge Pleraplysilla spinifera, has been synthesised. An alternative, less efficient, route to this type of furan, via acyclic keto-epoxides, is also discussed.