Application of Sublimation in the Synthesis and Crystal Growth of Organosulfones

The solvent-free elimination of sulfinic acid and aromatization of 1,6-trans-substituted bis(arylsulfone) trienes is reported. It is shown that sublimation can be used as a 'green' method to combine the thermal transformation of six trienes and the crystal growth of the resulting 4-(phenylsulfonyl)biphenyls. When the sublimation conditions are carefully controlled, high quality single crystals of the 4-(phenylsulfonyl)biphenyls are obtained. Theoretical modelling of the reaction using the simplified triene Ph-(CH)6-SO2H showed that the cyclization is energetically feasible and that the complete conversion is possible during the timescale of the sublimation. At temperatures slightly higher than the optimum sublimation temperature two of the trienes transformed into 1,4-cyclohexadienes that did not eliminate phenylsulfinic acid. A reaction mechanism involving a 1,3-hydrogen shift induced by free PhS• radicals is proposed for the formation of the 1,4-cyclohexadienes.

Heterogeneous copper-catalyzed synthesis of diaryl sulfones

A carbon-supported copper nanoparticle (Cu-NP) with high catalytic activity for the synthesis of diaryl sulfones is reported. For the first time, this Cu-NP is proved to be able to effectively promote the reaction of arylboronic acids and arylsulfonyl hydrazides to generate diaryl sulfones at room temperature. The reaction shows excellent substrate universality, and substrates with different substituents can undergo the reaction smoothly, leading to the desired products in good yields. The Cu-NP is found to be made of low valence Cu based on XRD. Hence, the reaction catalyzed by the Cu-NP is believed to involve a Cu-mediated organometallic cycle.

F--Free Deoxyhydrotrifluoromethylation of α-Keto Esters with Ph3P+CF2CO2-: Synthesis of α-CF3-Substituted Esters

Trifluoromethylated compounds are usually obtained via trifluoromethylation reaction by the use of CF₃SiMe₃ and NaSO₂CF₃, Umemoto's and Togni's reagents. Here, an external fluorine anion-free direct deoxyhydrotrifluoromethylation of α-keto esters with a difluoromethylating reagent has been achieved, in which the employment of water can promote the dissociation of the CF₂ group to form a CF₃ moiety, which provides the successful transformation. The current protocol demonstrates one of the most practical approaches to generate α-trifluoromethyl esters with a broad substrate scope and high functional group compatibility, in which it is applicable to late-stage modification of biologically active compounds and can be readily scaled up. Mechanistic investigation reveals that an in situ-generated gem-difluoroalkene intermediate is decomposed by water, giving rise to acid fluoride and HF.

Facile synthesis of biarylmethanes and tetrasubstituted arenes via a base-mediated [3 + 3] benzannulation reaction of Morita–Baylis–Hillman adducts and unsaturated sulfones

A regioselective DBU-mediated [3 + 3] benzannulation reaction of 1,3-bis-sulfonyl propenes and Morita–Baylis–Hillman (MBH) bromides to afford bis-sulfonyl biarylmethanes/arenes is described.

Synthesis of multisubstituted arylsulfones via a one-pot, three-component [3 + 3] benzannulation reaction

A one-pot, three-component [3 + 3] benzannulation reaction of α,β-unsaturated carbonyl compounds, bromoallylic sulfones, and sodium sulfinates provided multisubstituted arylsulfones with moderate to good yields.