Synthesis of N-Alkylpyridin-4-ones and Thiazolo[3,2-a]pyridin-5-ones through Pummerer-Type Reactions

Abstract

N-Alkylated 4-pyridones were obtained through a one-pot procedure involving either normal or interrupted Pummerer reactions between triflic anhydride-activated sulfoxides and 4-fluoropyridine derivatives, followed by hydrolysis. On the other hand, triflic anhydride-activated benzyl 6-fluoro-2-pyridyl sulfoxide could react with alkenes or alkynes to afford thiazolo­[3,2-a]­pyridin-5-ones, via the pyridinium salt intermediates.

Triflic Anhydride (Tf2O)-Activated Transformations of Amides, Sulfoxides and Phosphorus Oxides via Nucleophilic Trapping

“…Realizing the significant biological and pharmaceutical activities of heterocyclic compounds, the Li group employed benzyl 6-fluoro-2pyridyl sulfoxides 51a, 51b along with alkenes 51c and alkynes 51d to develop a new synthetic method for thiazolo[3,2-a]pyridin-5-ones 51e, 51f via interrupted Pummerer reaction (Scheme 51). 88 Various substituted -methylstyrenes as nucleophile partners provided the desired products of pyridinones while 1,1-diphenyl ethylene substrate gave no target product due to steric effects. It is worth mentioning that this reaction proceeds stereospecifically, as the trans-1,2-diphenyl ethylene substrate produces the trans-diastereomer product 51g; no single bond rotation was enabled prior to the cyclization.…”

Cu/Ni-Catalyzed Cyanomethylation of Alkenes with Acetonitrile for the Synthesis of β,γ-Unsaturated Nitriles

“…1-(tert-Butyl)-4-(prop-1-en-2-yl)benzene (1v). 22 Colorless oil, 76% yield (529 mg). The eluent used was ethyl acetate/petroleum ether (1:100): 1 H NMR (400 MHz, chloroform-d) δ 7.42 (dd, J = 8.3, 1.6 Hz, 2H), 7.35 (dd, J = 8.5, 1.5 Hz, 2H), 5.35 (s, 1H), 5.04 (s, 1H), 2.14 (s, 3H), 1.32 (s, 9H).…”

Sulfur-Mediated Allylic C–H Arylation, Epoxidation, and Aziridination

“…Based on many precedents for the reactions with alkenes and alkynes involving activated sulfoxides, , we hypothesize that allylic sulfur ylides could be directly generated from simple olefins, through electrophilic addition of activated sulfoxides with olefins, followed by subsequent deprotonation, which could then react with arylboronic acids via 1,2-metalate shift and hydrolysis, or with aldehydes/aldimines via the Corey–Chaykovsky reaction, to give the desired allylic functionalized products (Scheme ).…”