A Cyclic Vicinal Bis(tetraketone) and Structural Investigations of Formoins

Investigations of simple formoins such as 2,5‐bis(1,1‐dimethyl‐2‐phenylethyl)‐2,4‐dihydroxyfuran‐3(2 H )‐one ( 17 ), benzoylformoin ( 18 ), p ‐toluoylformoin ( 19 ), pivaloylformoin ( 20 ), and the 2,4‐dihydroxy‐2,5‐bis(heterocycl‐2‐yl)furan‐3‐ones 21 − 23 (heterocycle = furan, thiophene, selenophene) by NMR spectroscopy in DMSO showed the dihydroxyfuranone skeleton and not an enediol structure. The formoin 17 was oxidized to the corresponding tetraketone 10 . The intermolecular double benzoin condensation of 1,4‐bis(2,2dimethyl‐3,4‐dioxobutyl)benzene ( 27 ) affords, in low yield, the bis(formoin) 29 , and this could be oxidized to provide 2,2,2′,2′,7,7,7′,7′‐octamethyl[8.8]paracyclophan‐3,3′,4,4′5,5′6,6′‐octaone ( 9 ). The molecular structures of 17 and 29 , the monohydrate of 10 ( 30 ), and also the dihydrate of 9 ( 31 ) are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)