Synthesis of naturally occurring bithiophenes: a photochemical approach

Abstract

temperature overnight. The excess trifluoroacetic anhydride and the solvent were removed under reduced pressure. The residue was dissolved in CH2C12 and the solution was washed with saturated aqueous NaHC03 solution, dried, and concentrated to give 17 (1.33 g, 92%) as a colorless oil: !H NMR (100 MHz) 4.05

Controlling Stereochemical Outcomes of Asymmetric Processes by Catalyst Remote Molecular Functionalizations: Chiral Diamino‐oligothiophenes (DATs) as Ligands in Asymmetric Catalysis

“…Purified by flash chromatography ( c ‐hex/AcOEt 7:3→6:4): yellow‐orange solid; m.p. 139–141 °C; 1 H NMR (200 MHz, CDCl 3 , 25 °C, TMS): δ = 9.94 (s, 1 H), 7.90 (d, J = 4.4 Hz, 1 H), 7.75 (d, J = 4.0 Hz, 1 H), 7.43 (d, J = 4.0 Hz, 1 H), 7.28 (d, J = 4.4 Hz, 1 H); 13 C NMR (50 MHz, CDCl 3 , 25 °C, TMS): δ = 182.5, 151.9, 147.0, 146.1, 144.4, 136.8, 129.5, 126.8, 124.7; IR (Nujol): $\tilde \nu $ = 2926(s), 2853(m), 1732(s), 1660(m), 1461(s), 1335(w), 1209(m) cm −1 ; UV/Vis (MeOH): λ abs = 340 nm; MS (70 eV): m / z (%): 239 (100), 209 (10), 149 (50), 121 (20) 32…”

Synthesis and reactivity of metal carbene complexes with heterobiaryl spacer substituents

“…The coordination of the metal fragment via an electrophilic carbene carbon atom has a significant effect on the electronic environment of the remaining ring protons of the heteroarene rings and is reflected in the downfield chemical shift values recorded in the 1 H NMR spectra of the heterocycles as spacers in the complexes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) compared to the heterocycles (S1-S4). The H3 resonances of thiophene rings are most affected by coordination of the carbene ligand to the transition metal.…”

Photochemical Behavior of Iodoheterocyclic Derivatives in the Presence of Electron-Poor Olefins

“…[10] 5-Iodothiophene-2-carbaldehyde (1b) was prepared from thiophene-2-carbaldehyde by reduction with LiAlH 4 , iodination with iodine and HgO, and subsequent oxidation of the alcohol with PCC. [11] 2-Iodo-5-nitrothiophene (1c) was obtained from 2-iodothiophene by reaction with nitric acid and Ac 2 O. [12] 5-Bromofuran-2-carbaldehyde (1d) was prepared from furan-2-carbaldehyde by reaction with bromine in dichloromethane.…”