Synthesis of Fluorenes<i>via</i>the Palladium-Catalyzed 5-<i>exo-dig</i>Annulation of<i>o</i>-Alkynylbiaryls
作者:Natalia Chernyak、Vladimir Gevorgyan
DOI:10.1002/adsc.200800765
日期:2009.5
The direct Pd-catalyzed intramolecular rapidly with electron-deficient benzene ring, which, in hydroarylation of o-alkynyl biaryls proceeded in highly combination with a substantial isotope effect observed, stereoselective manner producing fluorenes 2, the products of 5-exo-dig cyclization, in excellent yields. The cascade intermolecular arylation, incorporated in this transformation, allowed for efficient
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
A palladium-catalyzed decarbonylative annulation of 2-arylbenzoic acids with internal alkynes via C(sp2)–H activation has been developed. A series of phenanthrenes were produced in moderate to good yield with good functional group tolerance. The mechanism study indicated that the C(sp2)–H activation should be the rate-determining step during the reaction.