Characterization data (PDF), copies of 1 H and 13 C NMR spectra (PDF), crystal structure data (PDF). The Supporting Information is available free of charge on the ACS Publications website. CCDC 2133112 (Compound 3) and 2149746 (Compound 4) contains the supplementary crystallographic data for this study. The data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/structures.