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Remote Functionalization of C60 with Enantiomerically Pure cyclo-[2]-Malonate Tethers Bearing C12 and C14 Spacers: Synthetic Access to Bisadducts of C60 with the Inherently Chiral trans‑3 Addition Pattern

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journal contribution
posted on 02.08.2013, 00:00 by Maria Riala, Nikos Chronakis
In this Article, we describe the synthesis of two optically pure diols bearing a 1,2-diol moiety masked as an isopropylidene acetal group and long alkyl chains comprised of 12 and 14 carbon atoms, respectively. The synthetic methodology that was developed offers a general way for the synthesis of optically pure diols with long alkyl chains. Diols (−)-4 and (−)-9 were subjected to a condensation reaction with malonyl dichloride to afford two cyclo-[2]-malonate tethers that were separated by column chromatography in optically pure form. The bismalonates (−)-4b and (−)-9b proved to be excellent tethers for the regioselective Bingel functionalization of C60, furnishing in a regioselective manner the corresponding f,sC and f,sA trans-3 bisadducts with low diastereoselectivity but in very good to excellent total yields. In both cases, the formed trans-3 bisadducts were isolated in pure form by simple column chromatography and were fully characterized. The successful acetal deprotection of the synthesized trans-3 bisadducts afforded quantitatively the corresponding polyalcohols, which represent novel chiral fullerene compounds equipped with glycol moieties.