Direct preparation of benzylic manganese reagents from benzyl halides, sulfonates, and phosphates and their reactions: applications in organic synthesis
作者:YoungSung Suh、Jun-sik Lee、Seoung-Hoi Kim、Reuben D Rieke
DOI:10.1016/s0022-328x(03)00500-x
日期:2003.11
The use of highly active manganese (Mn)*, prepared by the Rieke method, was investigated for the direct preparation of benzylic manganese reagents. The oxidative addition of the highly active manganese to benzylic halides was easily completed under mild conditions. Moreover, benzylic manganese sulfonates and phosphates were prepared by direct oxidative addition of Mn* to the carbon–oxygen bonds of
Regioselective synthesis of 4-(2-oxoalkyl)pyridines via 1,4-dihydro-pyridine derivatives using silyl enol ethers and pyridinium salts
作者:Kin-ya Akiba、Yoshihiro Nishihara、Makoto Wada
DOI:10.1016/s0040-4039(00)88414-2
日期:——
– 87% yields. When 2, 2, 2-trichloroethyl chloroformate was employed, yields of the corresponding 1,4-dihydropyridines (0 were higher (80 – 100% yields). and were oxidized by oxygen or AgNO3 to give 4-(2-oxoalkyl)pyridines ( : 30 –65%).
Reactions of 5-methyl-2H-1, 4-thiazin-3 (4H) -one (4) with various N-acylpyridinium salts (7a-g) led to (N-acyldihydropyridyl) thiazinones (5a-g), oxidation of which yielded a new class of pyridylthiazinones (6a-g). These reactions were applied to the synthesis of other azaarylthiazinones. Some of these azaarylthiazinones, particularly 6- (4-pyridyl) thiazinones (6a, 14a and 14b) showed positive inotropic activity with little chronotropic effect on guinea pig left atria.
A Convenient Method for the Regioselective Synthesis of 4-Alkyl(aryl)pyridines Using Pyridinium Salts
作者:Kin-ya Akiba、Y\={u}ji Iseki、Makoto Wada
DOI:10.1246/bcsj.57.1994
日期:1984.7
(81–94%). The dihydropyridines were oxidized by oxygen to give 4-alkyl(aryl)pyridines (38–68%). Grignardreagents also reacted with 1-t-butyldimethylsilylpyridinium triflate with almost complete regioselectivity (>99%) to afford the corresponding 1,4-dihydropyridines, which were easily oxidized by oxygen to give 4-substituted pyridines in higher yields than above (58–70%).
The preparation of various 1-acyl-1,2-dihydropyridines with high regioselectivity by indium-mediated allylation of the corresponding 1-acylpyridinium salts is demonstrated. This is applied to the synthesis of (±)-dihydropinidines.