RESUMEN
Using dimethylsulfoxonium methylide as the methylene transfer reagent, 2a,8b-dihydrobenzo[b]cyclobute[d]pyran-3-ones were converted into 2,2'-biphenol derivatives as major products and dihydrodibenzofurans as minor products. The reaction mechanism was extrapolated from a deuteration experiment with CD2=S(O)(CD3)2.
Asunto(s)
Ciclobutanos/química , Dibenzofuranos/síntesis química , Fenoles/síntesis química , Compuestos de Sulfonio/química , Dibenzofuranos/química , Estructura Molecular , Fenoles/químicaRESUMEN
A highly efficient catalytic system for C-H activation has been worked out that involves inexpensive RuCl(3)·xH(2)O and a specific amount of PPh(3). This procedure has been successfully applied to a practical synthesis of angiotensin II receptor blockers (ARBs). The residual ruthenium that existed in the reaction mixture was thoroughly removed by treatment with properly selected metal scavengers. The new process permits ready access to the important class of drugs in a highly atom-economical and sustainable manner.
Asunto(s)
Antagonistas de Receptores de Angiotensina/síntesis química , Antihipertensivos/síntesis química , Losartán/síntesis química , Tetrazoles/síntesis química , Sales de Tetrazolio/síntesis química , Valina/análogos & derivados , Compuestos de Bifenilo/química , Catálisis , Quelantes/química , Humanos , Espectroscopía de Resonancia Magnética , Rutenio , Valina/síntesis química , ValsartánRESUMEN
1,2a-Disubstituted 1,2,2a,8b-tetrahydro-3H-benzo[b]cyclobuta[d]pyran-3-ones bearing an electron-withdrawing group at the 2a-position were treated with two equivalents of dimethylsulfoxonium methylide to give r-1,t-4a,t-9b-1,3-disubstituted 1,2,4a,9b-tetrahydrodibenzofuran-4-ols stereoconvergently regardless of the stereochemistry of the 1-position on the benzocyclobutapyran ring. This methodology was applied to the second-generation synthesis of (+/-)-linderol A, a melanin biosynthesis inhibitory natural product.