Studies on the [4 + 2] cycloaddition and allylic substitution of indole-fused zwitterionic π-allylpalladium

The zwitterionic π-allylpalladium species, also known as dipoles, are important synthons widely used in various reactions including cycloaddition and allylic substitution. This study reported the development of a new indole-fused zwitterionic π-allylpalladium precursor compound and its application in [4 + 2] cycloaddition and allylic substitution reactions. As a result, the synthesis of pyrrolo[3,2,1-ij]quinazolin-3-one and 7-vinyl indole compounds was achieved with moderate to good yields. Notably, the allylic substitution reaction exhibited excellent regio- and stereoselectivity.

Metal-Free Regioselective Hydrophosphorodithioation of Spirovinylcyclopropyl Oxindoles: Rapid Access to Allyl Dialkylphosphorodithioates

Phosphorodithioates are important substructures due to their great use in bioactive compounds and functional materials. A metal-free 1,5-addition of spirovinylcyclopropyl oxindoles have been developed by choosing P₄S₁₀ and alcohol as nucleophiles through the regioselective ring-opening of spirovinylcyclopropyl oxindoles. This method provides access to allylic organothiophosphates with high efficiency, wide functional group tolerance, good chemo- and regioselectivity, and E-selectivity. 1,3-Addition products were also prepared in high yield. Furthermore, the resulting organothiophosphates could be readily transformed into other allylic derivatives.

Copper and Photocatalytic Radical Relay Enabling Fluoroalkylphosphorothiolation of Alkenes: Modular Synthesis of Fluorine-Containing S-Alkyl Phosphorothioates and Phosphorodithioates

A photoredox and copper-catalyzed fluoroalkylphosphorothiolation of activated and unactivated alkenes via a radical relay mechanism is reported. By employing fluoroalkyl halides as radical precursors and P(O)SH or P(S)SH compounds as coupling partners, a wide range of β-monofluoroalkyl-, -difluoroalkyl-, -trifluoromethyl-, or -perfluoroalkyl-substituted S-alkyl phosphorothioates and phosphorodithioates can be easily constructed under mild conditions with good functional group tolerance. Furthermore, this modular reaction system can be successfully applied to late-stage functionalization of bioactive molecules.

Copper-Catalyzed Multicomponent Trifluoromethylphosphorothiolation of Alkenes: Access to CF3-Containing Alkyl Phosphorothioates

An unprecedented copper-catalyzed multicomponent radical-based reaction involving alkenes, P(O)H compounds, sulfur powder, and Togni reagent II at room temperature has been developed. A variety of highly functionalized CF₃-containing S-alkyl phosphorothioates can be directly prepared from a wide range of activated and unactivated alkenes. Moreover, this protocol highlights its potential in the late-stage functionalization of complex molecules and opens up a new avenue for the construction of C(sp³)-S-P bonds.

Copper-catalyzed thioamination of maleimides with diethylphosphorodithioate and amines

The first copper-catalyzed oxidative aminophosphorothiolation of maleimides with secondary alkylamines and diethylphosphorodithioate has been established.

Very short highly enantioselective Grignard synthesis of 2,2-disubstituted tetrahydrofurans and tetrahydropyrans

Phenones with elongated chains are shown to be excellent substrates for ligand-promoted asymmetric Grignard synthesis of tertiary alcohols. In turn this enables the simple, short and highly enantioselective (up to 96% ee) preparation of chiral 2,2-disubstituted THFs and THPs. Thus, asymmetric addition of Grignard reagents to γ-chlorobutyrophenones and δ-chlorovalerophenones takes place in the presence of a chiral diaminocyclohexyl-derived tridentate ligand and subsequent base-promoted intramolecular cyclisation occurs with complete retention of asymmetry. As examples of the methodology, we report the shortest syntheses of gossonorol, γ-ethyl-γ-phenylbutyrolactone and δ-methyl-δ-tolylvalerolactone, the joint-shortest and flexible synthesis of boivinianin A and the shortest formal syntheses of boivinianin B and yingzhaosu C.