Synthesis of Multisubstituted Triphenylenes and Phenanthrenes by Cascade Reaction of <i>o</i>-Iodobiphenyls or (<i>Z</i>)-β-Halostyrenes with <i>o</i>-Bromobenzyl Alcohols through Two Sequential C–C Bond Formations Catalyzed by a Palladium Complex
bearing both nucleophilic and electrophilic substituents, for the facile synthesis of polycyclic aromatic hydrocarbons. A palladium/electron-deficient phosphine catalyst efficiently coupled o-iodobiphenyls or (Z)-β-halostyrenes with o-bromobenzyl alcohols to afford triphenylenes and phenanthrenes, respectively. The present cascade reaction proceeded through deacetonative cross-coupling and sequential intramolecular
benzannulation with o-bromobenzyl alcohols enabled the facile construction of phenanthrene skeletons via the sequential multiple carbon–carbon bond formations. A variety of multisubstituted phenanthrenes were synthesized by the reaction of (Z)-β-halostyrenes with o-bromobenzyl alcohols as well as by the three-component coupling of alkynes, aryl bromides, and o-bromobenzyl alcohols. The electron-deficient phosphine
Substituent Effects on the Photogeneration and Selectivity of Triaryl Vinyl Cations
作者:Jan Willem J. van Dorp、Gerrit Lodder
DOI:10.1021/jo800687z
日期:2008.7.1
photogenerated vinyl cations 1+ depend on the α-aryl substituent, the β-aryl substituent, the leaving group X (= bromide or chloride), and the temperature at which the irradiations are carried out. Hammett correlation or noncorrelation of the α-aryl substituent effects with (excited-state) substituent constants indicates that the ions 1+ are formed directly from the excited states of 1X by heterolytic cleavage
Photolysis of vinyl bromides with cyanate anion In a two-phase system gave only isoquinolinones as the N-site attacked products. However, the photolysis with thiocyanate anion gave both the N-site attacked products, isothioquinolinones or vinyl isothiocyanates, and the S-site attacked products, vinyl thiocyanates.
乙烯基溴与氰酸根阴离子的光解在两相系统中仅产生异喹啉酮作为 N 位攻击产物。然而,用硫氰酸根阴离子光解得到 N 位攻击产物,异硫喹啉酮或乙烯基异硫氰酸酯,和 S 位攻击产物,乙烯基硫氰酸酯。
ISOQUINOLINE DERIVATIVES FROM THE RITTER-TYPE REACTION OF VINYL CATIONS
Both silver-assisted reaction of β-arylvinyl bromides and the photolysis in nitriles gave isoquinoline derivatives, indicating that the Ritter reaction involving a vinylcation took place.