Rh(iii)-catalyzed redox-neutral C–H [4 + 1] annulation of sulfoximines with α,α-difluoromethylene alkynes: diastereoselective synthesis of E-monofluoroalkenyl benzoisothiazole 1-oxides

Abstract

Novel cyclic fluorinated sulfoximines featuring an E-monofluoroalkenyl benzoisothiazole 1-oxide moiety as single diastereomers can be facilely accessed by Rh(III)-catalyzed redox-neutral [4+1] annulation of sulfoximines with α,α-difluoromethylene alkynes. The reaction proceeds...

A rhodium-catalyzed cascade C–H activation/annulation strategy for the expeditious assembly of pyrrolidinedione-fused 1,2-benzothiazines

“…5 Other Cn synthons such as diazo compounds, 6 pyridotriazoles, 7 α-MsO/TsO ketones, 8 dioxazol-5-ones, 9 ylides, 10 and vinylene carbonates 11 have recently become complementary alternatives to sulfoximines in the [4 + 2] annulation to form six-membered cyclic sulfoximines (Scheme 1a). Additionally, Yi and Dong independently disclosed a cascade [4 + 1] annulation pathway for the synthesis of benzoisothiazole derivatives through rhodium( iii )-catalyzed N -directed ortho C–H activation reactions of sulfoximines with α,α-difluoromethylene alkynes (Scheme 1b) 12 or activated olefins (Scheme 1c). 13 Very recently, a chiral Ru( ii )-catalyzed asymmetric [4 + 3] annulation of sulfoximines with α,β-unsaturated ketones to construct chiral benzothiadiazine-1-oxides (Scheme 1d) was reported.…”