Diverse Reactivity of Dienes with Pentaphenylborole and 1-Phenyl-2,3,4,5-Tetramethylborole Dimer |
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Authors: | J. J. Baker Khadilah H. M. Al Furaiji O. Tara Liyanage Dr. David J. D. Wilson Dr. Jason L. Dutton Dr. Caleb D. Martin |
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Affiliation: | 1. Department of Chemistry and Biochemistry, Baylor University, One Bear Place 97348, Waco, TX, 76798 USA;2. Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, 3086 Australia |
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Abstract: | The reactions of a monomeric borole and a dimeric borole with 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene were investigated. The monomeric borole reacted at ambient temperature whereas heat was required to crack the dimer to form the monomer and induce reactivity. 2,3-Dimethyl-1,3-butadiene reacts to give diverse products resulting from a cycloaddition process with the B−C moiety of the boroles acting as a dienophile, followed by rearrangements to furnish bicyclic species. For 1,3-cyclohexadiene, a [4+2] process is observed in which 1,3-cyclohexadiene serves as the dienophile and the boroles as the diene partner. The experimental results are corroborated with mechanistic theoretical calculations that indicate boroles can serve as either a diene or dienophile in cycloaddition reactions with dienes. |
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Keywords: | anti-aromaticity boroles boron heterocycles cycloaddition Diels–Alder reactions |
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