由2-(1-芳基-2-甲氧基乙烯基)-1-溴苯1制备4-芳基香豆素(= 4-芳基-1 H --2-苯并吡喃-1-酮)6。用BuLi和1-甲酰基哌啶连续处理这些溴苯乙烯,得到(E)-和(Z)-2-(1-芳基-2-甲氧基乙烯基)苯甲醛的混合物2。(Z)-异构体的水解 用HBr进行氧化,然后将所得的1 H -2-苯并吡喃-1-醇衍生物4(和5)氧化氯铬酸吡啶鎓(PCC ),得到所需的产物。
Synthesis of 3-Aryl-2-methoxyinden-1-one (<i>Z</i>)-Phenylhydrazones<i>via</i>Hydrobromic Acid-Mediated Cyclization of 2-(1-Aryl-2-methoxyethenyl)benzaldehyde Phenylhydrazones
2‐(1‐Aryl‐2‐methoxyethenyl)benzaldehydes 2, obtained by successive treatment of 1‐(1‐aryl‐2‐methoxyethenyl)‐2‐bromobenzenes 1 with BuLi and 1‐formylpiperidine, were transformed to the corresponding phenylhydrazones 3 on treatment with PhNHNH2. When these hydrazones were allowed to react with conc. HBr, cyclization, followed by dehydrogenation with air occurred, furnished 3‐aryl‐2‐methoxyinden‐1‐one
zopyran‐1‐ones), 4‐substituted 3,4‐dihydro‐3‐methoxyisocoumarins 2, can be obtained by a one‐pot process from α‐substituted 2‐bromo‐β‐methoxystyrenes 1. Thus, lithium 2‐(1‐aryl(or methyl)‐2‐methoxyethenyl)benzoates are conveniently generated via the Br/Li exchange between 1 and BuLi, followed by the action of CO2 on the resulting α‐substituted 2‐lithio‐β‐methoxystyrenes. Upon treating with concentrated
可以通过一锅获得一种新型的异香豆素(= 1 H-异色n-1-酮= 1 H -2-苯并吡喃-1-酮),4-取代的3,4-二氢-3-甲氧基异香豆素2。由α-取代的2-溴-β-甲氧基苯乙烯制备1。因此,通过1和BuLi之间的Br / Li交换可方便地生成2-(1-芳基(或甲基)-2-甲氧基乙烯基)苯甲酸锂,然后通过CO 2对生成的α-取代的2-lithio-苯甲酸作用β-甲氧基苯乙烯。在室温下用浓盐酸处理后,这些苯甲酸锂会发生内酯化反应,从而以相对较高的收率提供所需的3,4-二氢异香豆素2。
Synthesis of 1,3-Diaryl-2-methoxyindenes by Hydriodic Acid–Catalyzed Cyclization of Aryl[2-(1-aryl-2-methoxyvinyl)phenyl]methanols
two-step method for the synthesis of 1,3-diaryl-2-methoxyindenes from1-(1-aryl-2-methoxyvinyl)-2-bromobenzenes has been developed. Thus, the reaction of 2-(1-aryl-2-methoxyvinyl)phenyllithiums, generated in situ by halogen–lithium exchange between 1-(1-aryl-2-methoxyvinyl)-2-bromobenzenes and butyllithium, with aromatic aldehydes gives aryl[2-(1-aryl-2-methoxyvinyl)phenyl]methanols, which in turn are treated
2-bromo-β-methoxystyrenes. Thus, the reaction of α-substituted 2-lithio-β-methoxystyrenes, generated by the bromine-lithium exchange between α-substituted 2-bromo-β-methoxystyrenes and butyllithium, with epoxides gives the corresponding 2-(methoxyvinyl)phenethyl alcohols. These undergo cyclization with a loss of methanol on treatment with a catalytic amount of hydriodicacid to give the desired products.