... Tetrahedron: Asymmetry. Volume 13, Issue 6, 19 April 2002, Pages 659–665. ... Reactions were monitored by thin-layer chromatography carried out on silica gel coated glass plates (60F 254 , Merck) 1 H and 13 C NMR spectra were recorded on Bruker AC-200 or Avance 400 ...