6533b852fe1ef96bd12ab933

RESEARCH PRODUCT

Conformational Control of Metallocene Backbone by Cyclopentadienyl Ring Substitution: a New Concept in Polyphosphane Ligands Evidenced by “Through-Space” Nuclear Spin-Spin Coupling. Application in heteroaromatics arylation by direct C–H activation

subject

description

The present study deals with the conformational control of the metallocene backbone within ferrocenyl polyphosphane ligands and their performance in the highly topical palladium-catalyzed heteroaromatics arylation by direct C−H activation. New substituted cyclopentadienyl rings were synthesized, which allowed the assembling of original tri- and diphosphanes. The bulky cyclopentadienyl lithium salts diphenylphosphino-3-(triphenyl)methylcyclopentadienyllithium (4) and 1,2-bis(diphenylphosphino)-4-(triphenyl)methylcyclopentadienyllithium (5) were prepared in excellent yield. The assembling of these new hindered cyclopentadienyl salts (Cp) with other Cp fragments was performed in order to prepare ferrocenyl ligands with controlled conformation. A comparison of conformations of 1,1′,2-tris(diphenylphosphino)-3′,4-di-tert-butylferrocene (3) and 1,1′,2-tris(diphenylphosphino)-3′-(triphenyl)methyl-4-tert-butylferrocene (6) allowed us to determine, for the first time, the conditions of an efficient control of the ...