Synthesis of Novel Heterocycles via Palladium Catalyzed Reactions

Abstract

All solvents were distilled prior to use. Petroleum ether refers to fraction boiling in the range 60-80 °C. DMF and DCM were dried over CaH2, distilled, and stored over 3Å molecular sieves in sealed container. THF was distilled over sodium and benzophenone. All the reactions were carried out under argon or nitrogen or oxygen atmosphere and anhydrous conditions unless otherwise stated. Analytical thin-layer chromatography (TLC) was performed on Silica gel 60 F254 aluminium TLC sheets. Visualization of the developed chromatogram was performed by UV absorbance or iodine exposure. For purification, column chromatography was performed using 100-200 mesh or 230-400 mesh silica gels. All the reagents including PdCl2, Pd(OAc)2, PdCl2(PPh3)2, Pd(PPh3)4 were purchased from Aldrich, Merck, Alfa-Aesar etc. 1H and 13C NMR spectra were recorded using a Brüker Advance 300 or 600 MHz using tetramethylsilane (TMS) as internal standard. Chemical shifts (δ) were given from TMS (δ = 0.00) in parts per million (ppm) with the residual protons of deuterated solvent used [CDCl3: 1H NMR δ = 7.26 ppm (s); 13C NMR δ = 77.16 ppm (t)]. Coupling constants (J) were expressed in Hertz (Hz) and spin multiplicities were given as s (singlet), d (doublet), dd (double doublet), t (triplet), m (multiplet) and br (broad). All 13C NMR spectra were obtained with complete proton decoupling. Mass spectra were recorded in ESITOF or JEOL JMS600 or GCMS-SHIMADZU-QP5050A DI-EI mass spectrometer. Infrared spectra were obtained on JASCO FT/IR-4200 infrared spectrometer as neat or KBr plate. Crystallographic data were obtained using Brüker Kuppa Apex 2 instrument