Solid-phase organic synthesis of 4-alkenyl-1-naphthols
A new method for the solid-supported synthesis of 4-alkenyl-1-napthol derivatives by sequential immobilization of naphthalenediol, triflation and Heck coupling reaction is described. The microwave-assisted reaction of trityl chloride resin with 1,4-napthalenediol produces the resin-bound naphthols. The triflation reaction with 4-nitrolphenyl triflate furnishes the corresponding resin-bound naphthalenyl triflate. The palladium-catalyzed reaction of naphthalenyl triflate with various olefins, followed by the TFA cleavage of the resulting resin-bound products produces the corresponding 4-alkenyl-1-napthol derivatives in moderate yields. ^ An attempted method to prepare 2,3,4-trisubstituted naphthol derivatives by sequential Dötz benzannulation, triflation, and Heck cross-coupling reaction is described. The microwave-assisted Dötz benzannulation of resin-bound Phenyl Fischer carbene complex with various alkynes, followed by the oxidative cleavage of the resin-bound 2,3-disubstituted naphthols gives the corresponding 2,3-disubstituted-1,4-napthoquinones in good to moderate yields. The triflation of these resin-bound naphthols with 4-nitrophenyltriflate, followed by the microwave assisted palladium-catalyzed Heck cross-coupling reaction of the resulting resin-bound product did not afford the corresponding 2,3,4-trisubstituted-1-naphthol derivatives. A plausible mechanism is proposed to explain the failure of this palladium-Heck coupling reaction. ^ A new deboronation reaction to prepare substituted aromatic compounds is described. The reaction of PL-Wang-Br with boronic acids, followed by the TFA cleavage of the resulting resin-bound product affords the corresponding substituted aromatic compounds in moderate yields. A plausible mechanism is proposed to account for the formation of products. ^
Agniparthi, Srinivas, "Solid-phase organic synthesis of 4-alkenyl-1-naphthols" (2006). ETD Collection for University of Texas, El Paso. AAI1436524.