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Fullerenes research paper was awarded by the Academy of Athens

Wednesday, 13 April 2016

cyclopropyl


Manolis D. Tzirakis and Michael Orfanopoulos
J. Am. Chem. Soc. 2009, 131, 4063-4069
DOI: 10.1021/ja808658b

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Acyl Radical Reactions in Fullerene Chemistry: Direct Acylation of [60]Fullerene through an Efficient Decatungstate-Photomediated Approach

The Academy of Athens in December 2011 awarded to Manolis D. Tzirakis (PhD 2009, Department of Chemistry) the prize "Hildegard, widow of Leonidas Zervas" accompanied by a monetary prize of 5000 euros. This award is classified to the Section of Sciences of the Academy of Athens and is granted to an original scholarly paper in organic chemistry, published within 2008-2010.
In this work, a versatile and highly efficient photochemical methodology for the direct acylation of C60 has been developed. This approach utilizes a wide variety of acyl radicals derived from aldehydes through a hydrogen atom abstraction process mediated by tetrabutylammonium decatungstate [(n-Bu4N)4W10O32]. The single addition reaction of these acyl radicals to [60]fullerene proceeded selectively to afford a novel class of previously unexplored fullerene-based materials. Product analysis of this reaction showed that decarbonylation and acylation pathways compete when a tertiary or phenylacetyl aldehyde is the starting material. However, a decrease of the reaction temperature was found to be effective in overcoming the decarbonylation encountered in certain acyl radical additions to C60; the carbonyl radical addition precedes decarbonylation even in the cases where the decarbonylation rate constant exceeds 106 s-1 (i.e., phenylacetaldehyde). The regiochemistry of the t-butyl radical addition was also found to be thermally controlled. The present methodology is directly applicable even in the cases of the cyclopropyl-substituted aldehydes, where rapid rearrangement of the cyclopropyl acyl radical intermediate can potentially occur. A mechanistic approach for this new reactivity of C60 has been also provided, based mainly on intra- and intermolecular deuterium isotope effect studies.
Original publication: http://pubs.acs.org/doi/abs/10.1021/ja808658b
Highlighted in SYNFACTS 2009, 7, 735: https://www.thieme-connect.de/DOI/DOI?10.1055/s-0029-1217221

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