A One-Pot Bicycloannulation Method for the Synthesis of Tetrahydroisoquinoline Systems
摘要:
A highly effective method for the synthesis of the core indolo[2,3-a]quinolizidine skeleton found in yohimbine is described. The reaction of N-monosubstituted thioamides with bromoalkenoyl chlorides furnishes thioisomunchnones as transient 1,3-dipoles that undergo ready intramolecular cycloaddition across the tethered pi-bond to give thio-bicycloannulated products in a one-pot operation. The stereochemical outcome of the intramolecular reaction is the consequence of an endo cycloaddition of the neighboring-bond across the transient thioisomunchnone dipole. A major limitation of the method is that when a hydrogen is present in the alpha-position of the thioamide the initially formed thio-N-acyliminium ion undergoes proton loss to produce a S ,N-ketene acetal at a faster rate than dipole formation. Treatment of tetrahydro-beta-carboline-1-thione with 2-bromooct-7-enoyl chloride followed by reductive removal of sulfur from the cycloadduct resulted in the formation of (+/-)-alloyahimbanone. Attempts to cycloadd the thioisomunchnone dipole across several nucleophilic-bonds failed, and instead, products derived from cyclization of the pi-bond onto the initially formed thio-N-acyliminium ion were formed. The resulting N,S-ketals were further converted into several tetrahydroisoquinoline alkaloids in good yield.
Photochemically induced cyclization of N-[2-(o-styryl)phenylethyl]acetamides and 5-styryl-1-methyl-1,2,3,4-tetrahydroisoquinolines: new total syntheses of 1-methyl-1,2,3,4-tetrahydronaphtho[2,1-f]isoquinolines
作者:Elena Martı́nez、Juan C Estévez、Ramón J Estévez、Luis Castedo
DOI:10.1016/s0040-4020(01)00041-2
日期:2001.3
Two new total syntheses of 1-methyl-1,2,3,4-dihydronaphtho[1,2-f]isoquinolines are based on the construction of their phenanthrene ring system by photochemicallyinducedcyclization of N-2-[(E)-2-phenyl-1-ethenyl]phenylethyl}acetamides or 1-methyl-5-[(E)-2-phenyl-1-ethenyl]-1,2,3,4-tetrahydroisoquinolines.
1-甲基-1,2,3,4-二氢萘并[1,2- f ]异喹啉的两个新的总合成是基于通过光化学诱导的N- 2-[(E) -2-苯基-1-乙烯基]苯基乙基}乙酰胺或1-甲基-5-[(E)-2-苯基-1-乙烯基] -1,2,3,4-四氢异喹啉。
Illicit heroin manufacturing by-products: capillary gas chromatographic determination and structural elucidation of narcotine- and norlaudanosine-related compounds
作者:Andrew C. Allen、Donald A. Cooper、James M. Moore、Manfred. Gloger、Helmut. Neumann