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.