Facile [3+2] dimerization and formal dehydrogenative coupling mode of a cyanophenylphosphaallene |
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Authors: | Shigekazu Ito Sou Hashino Masaaki Yoshifuji Masae Takahashi Yoshiyuki Kawazoe |
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Institution: | a Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578, Japan b Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487-0336, USA c Institute for Material Research, Tohoku University, Katahira 2-1-1, Aoba, Sendai 980-8577, Japan |
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Abstract: | Due to a facile head-to-tail 3+2] dimerization, even a sterically demanding group such as the Mes∗ (2,4,6-tri-tert-butylphenyl) group around the P C C moiety did not allow us to isolate 3-(4-cyanophenyl)-1-(2,4,6-tri-tert-butylphenyl)-1-phosphaallene from the elimination reaction of 2-bromo-3-(4-cyanophenyl)-1-(2,4,6-tri-tert-butylphenyl)-1-phosphaprop-1-ene with DBU (1,8-diazabicyclo5.4.0]undec-7-ene), and the corresponding 1,4-diphosphafulvene containing cyano groups was obtained and characterized. Theoretical studies on the 3+2] dimerization of phosphaallene characterize possible intermediates affording 1,4-diphosphafulvenes and also suggest the cyano group effect to facilitate the saturation of the P C double bonds. On the other hand, 1,2-bis(4-cyanophenyl)-3,4-bis(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutene was obtained from 2-bromo-3-(4-cyanophenyl)-3-trimethylsiloxy-1-(2,4,6-tri-tert-butylphenyl)-1-phosphaprop-1-ene together with the 3-(4-cyanophenyl)-1-phosphaallene. |
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Keywords: | Phosphaalkenes Phosphorus heterocycles Oligomerization DFT calculations |
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