Experimental Studies
All chemicals were obtained from Sigma-Aldrich, and were used without further purification. 1H NMR and 13C NMR spectra were recorded on a Varian 200 MHz or Bruker Avance DPX 400 MHz spectrometer using CDCl3 as a solvent and tetramethylsilane (TMS) as an internal standard. Splitting patterns are designated as follows; s, singlet; d, doublet; m, multiplet. Chemical shift (d) values are given in ppm.