Tridentate Sulfoxide-N-olefin Hybrid Ligands in Rhodium-Catalyzed Asymmetric Allylic Substitution.

A well-defined tridentate chiral sulfoxide-N-olefin ligand has been designed and applied in rhodium-catalyzed asymmetric allylic substitutions of racemic allylic carbonates, providing the branched allylic products in good yields with good to high enantioselectivities and excellent regioselectivities. This reaction mechanism, which involves the possible hemilability of olefin coordination on sulfoxide-N-olefin hybrid ligands with rhodium, is elaborated as well.

Ir-Catalyzed Chemo-, Regio-, and Enantioselective Allylic Enolization of 6,6-Dimethyl-3-((trimethylsilyl)oxy)cyclohex-2-en-1-one Involving Keto-Enol Isomerization.

The utilization of 6,6-dimethyl-3-((trimethylsilyl)oxy)cyclohex-2-en-1-one made from an unsymmetrical 4,4-dimethylcyclohexane-1,3-dione in iridium-catalyzed allylic enolization involving keto-enol isomerization is accomplished under mild conditions. The chemoselectivity, regioselectivity, and enantioselectivity are facilitated by the quaternary carbon and adjusting the reaction conditions. This method provides the substituted 2-(but-3-en-2-yl)-3-hydroxy-6,6-dimethylcyclohex-2-en-1-ones in good to high yields with high level of chemo-, regio-, and enantioselectivities. The chiral carbon-fluorine bond formation is induced by an adjacent chiral carbon center of the allylated 3-hydroxy-6,6-dimethylcyclohex-2-en-1-one, as well.

Chemoselective, Regioselective, and Enantioselective Allylations of NH2OH under Iridium Catalysis.

The utilization of unprotected NH2OH, which is not only an oxygen nucleophile but also a nitrogen nucleophile, in iridium-catalyzed allylic substitution is realized under mild conditions. The chemoselectivity, stereoselectivity, and multiple allylation are controlled by adjusting the reaction conditions. This method produces the N-(1-allyl)hydroxylamines in good to high yields with high level of chemoselectivities, regioselectivities, and enantioselectivities. The application of allylated hydroxylamine (R)-3a in the synthesis of diallylated hydroxylamine 6 is achieved, along with an excellent diastereomeric ratio.

Diasteroselective and Enantioselective Ir-Catalyzed Allylic Substitutions of 1-Substituted 1-Fluoro-1-(arenesulfonyl)methylene Derivatives.

diasteroselective and enantioselective Ir-catalyzed allylic substitutions of 1-substituted 1-fluoro-1-(arenesulfonyl)methylene derivatives are presented, which afford the fluorinated allyl products with two chirality centers. The steric demand of 1-substituted 1-fluoro-1-(arenesulfonyl)methylene derivatives and allylic substrates has a great influence on the dr values of these reactions. The transformation of the branched allyl product into the fluorinated 3,4-dihydro-2H-pyrrole 1-oxide was discussed, as well.

Enantioselective synthesis of fluorinated branched allylic compounds via Ir-catalyzed allylations of functionalized fluorinated methylene derivatives.

Enantioselective introduction of the functionalized monofluorinated methylenes into the allylic fragment under Ir catalysis has been realized, which gave the fluorinated branched allyl products in good to high yields with excellent regio- and enantioselectivities.