3S) stereoisomers. The presence of a hydroxy or a methoxy group at the 7-postiion enhanced the inhibitory potency, and the additional substitutions at the 6- or 8-position in the A ring increased potency and stereospecificity. A representative compound, (2R,3R)-2′,3′,7,8-tetrahydroxyflavanonol 5e, had an IC50 value of 17 µM, whereas its (2S,3S) stereoisomer did not inhibit NO production at all at a
Synthesis of Substituted 3-Iodocoumarins and 3-Iodobutenolides via Electrophilic Iodocyclization of Ethoxyalkyne Diols
作者:Maddi Sridhar Reddy、Nuligonda Thirupathi、Madala Hari Babu、Surendra Puri
DOI:10.1021/jo400499r
日期:2013.6.21
A convenient and general synthesis of various 4-substituted 3-iodocoumarins and 4,5-disubstituted 3-iodobutenolides is described via an exclusive 6-endo-dig iodocyclization of 3-ethoxy-1-(2-alkoxyphenyl)-2-yn-1-ols and 5-endo-dig iodocyclization of 1-alkoxy-4-ethoxy-3-yn-1,2-diols, respectively. The reaction is carried out under very mild conditions using I2 in CH2Cl2 or toluene at room temperature
A novel and general route to diverse A-ring aromatic trichothecanes via cyclobutanes
作者:Hideo Nemoto、Junji Miyata、Keiichiro Fukumoto
DOI:10.1016/0040-4020(96)00549-2
日期:1996.7
A novel and generally applicable approach to A-ringaromatictrichothecane 2 was achieved by the regiocontrolled cyclization of 25, 26, 29, and 30 as a key step, followed by stereoselective construction of the epoxide ring. This manuscript also described the regiocontrolled ring expansion of the olefinic cyclobutanols 19–22 to give the enones 23 and 24 which were the important intermediates in this