ABSTRACT
Soft enolization conditions are revealed to be markedly better than the typically applied hard enolization protocols for regioselective enoxysilane formation from unsymmetrical 3-substituted cycloalkanones. Five-, six-, and seven-membered cycloalkanones each with 3-methyl, 3-isopropyl, or 3-phenyl substituents were investigated, and in all but one case, regioselectivities were ≥11:1 for enolization away from the substituent. These results are complementary to the regiospecific enoxysilane formation derived from cycloalkenone conjugate addition/enolate silylation.
Subject(s)
AlcoholsABSTRACT
An anionic oxy-Cope/transannular Michael addition cascade converts a spirocyclic architecture-readily available by Diels-Alder cycloaddition-into the hydrophenalene carbon skeleton of the pseudopterosin aglycones. Oxidation of the resulting cyclohexenone ring to the phenol that is characteristic of the targets completes a short formal synthesis.
Subject(s)
Cyclohexanones/chemistry , Diterpenes/chemical synthesis , Glycosides/chemical synthesis , Phenols/chemistry , Anions/chemistry , Cycloaddition Reaction , Diterpenes/chemistry , Glycosides/chemistry , Molecular Structure , StereoisomerismABSTRACT
Diastereoselective oxyarylation of N-protected 2-alkylindoles with commercially available boronic acids and TEMPO as a mild oxidant to give N-protected 2-aryl-2-alkyl-3-(2-chloroacetoxy)indolines is described. Reactions are easy to conduct, and product indolines containing a fully substituted C-center are obtained in good yields with good to excellent selectivities.
Subject(s)
Boronic Acids/chemistry , Indoles/chemistry , Palladium/chemistry , Catalysis , Molecular Structure , StereoisomerismABSTRACT
Ir-phosphinomethyl-oxazoline complexes have been identified as efficient, highly enantioselective catalysts for the asymmetric hydrogenation of 3,3-disubstituted allylic alcohols and related homoallylic alcohols. In contrast to other N,P ligand complexes, which require weakly coordinating solvents, such as dichloromethane, these catalysts perform well in more ecofriendly THF or 2-MeTHF. Their synthetic potential was demonstrated with the formal total synthesis of four bisabolane sesquiterpenes.