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Synfacts 2011(9): 0950-0950
DOI: 10.1055/s-0030-1261001
DOI: 10.1055/s-0030-1261001
Synthesis of Heterocycles
© Georg Thieme Verlag
Stuttgart ˙ New York
An Efficient Protocol for the Synthesis of Dibenzodithiapentalene
T. H. Jepsen, M. Larsen, M. Jørgensen, M. B. Nielsen*
University of Copenhagen and Discovery Chemistry and DMPK, Valby, Denmark
Further Information
Publication History
Publication Date:
19 August 2011 (online)
Significance
Reported is the improved synthesis of dibenzodithiapentalene (6) employing an SNAr approach. Directed ortho metalation of 1 followed by oxidative dimerization using PhNO2 afforded the desired biaryls 2 and 3 in good yield. Subsequent acidic deprotection gave the diol 4 and dithiol 5, ready for the final cyclizations. Exposure of dithiol 5 to standard SNAr conditions (Cs2CO3, DMSO, high temperature) led smoothly to the desired pentalene in an impressive yield. However, when diol 4 was subjected to similar reaction conditions, none of the desired product was obtained. Instead, intermolecular condensation produced macrocyclic 8 as the major product.