Reactions of calix[4]arenes with 1,3-dibromopropane and 1,5-dibromopentane. Identification of products using 1D and 2D NMR techniques, and X-ray crystallography

Attempts to bridge a calix[4]arene with a three-carbon bridge using 1,3-dibromopropane and NaH/DMF led to elimination reactions. Using K2CO3/CH3CN, three new calixarenes were obtained: a biscalixarene (8), a novel bridged calixarene (9), and a partial cone calixarene (10). Attempts to bridge a calix[4]arene with a five-carbon bridge using 1,5-dibromopentane and K2CO3/CH3CN led to a (known) biscalixarene (12) and a novel monobridged calixarene (13). To characterize the new calixarenes, a variety of 1D and 2D NMR techniques, mass spectrometry, and in some cases X-ray crystallography were used.