Publication | Closed Access
Reactions of Boron-Derived Radicals with Nucleophiles
42
Citations
44
References
2016
Year
Reactions of phenanthrenedione- and pyrenedione-derived borocyclic radicals, C<sub>n</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub><sup>•</sup> (n = 14 (1), 16 (3)), with a variety of nucleophiles have been studied. Reaction of 1 with P(t-Bu)<sub>3</sub> affords the zwitterion 3-(t-Bu)<sub>3</sub>PC<sub>14</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (5) in addition to the salt [HP(t-Bu)<sub>3</sub>][C<sub>14</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>] (6). In contrast, the reaction of 1 with PPh<sub>3</sub> proceeds to give two regioisomeric zwitterions, 1-(Ph<sub>3</sub>P)C<sub>14</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (7a) and 3-(Ph<sub>3</sub>P)C<sub>14</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (7b), as well as the related boronic ester C<sub>14</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>) (2). In a similar fashion, 3 reacted with PPh<sub>3</sub> to give 3-(Ph<sub>3</sub>P)C<sub>16</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (8a), 1-(Ph<sub>3</sub>P)C<sub>16</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (8b), and boronic ester C<sub>16</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>) (4). Reactions of secondary phosphines Ph<sub>2</sub>PH and tBu<sub>2</sub>PH with 3 yield 3-(R<sub>2</sub>PH)C<sub>16</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (R = Ph (9), t-Bu (10)). The reaction of 1 with N-heterocyclic carbene IMes afforded 3-(IMes)C<sub>14</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (11) and [IMesH][C<sub>14</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>] (12), while the reactions with quinuclidine and DMAP afforded the species 3-(C<sub>7</sub>H<sub>13</sub>N)C<sub>14</sub>H<sub>7</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> (13) and [H(NC<sub>7</sub>H<sub>13</sub>)<sub>2</sub>][C<sub>14</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>] (14), and the salt [9,10-(DMAP)<sub>2</sub>C<sub>14</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>][C<sub>14</sub>H<sub>8</sub>O<sub>2</sub>B(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>] (15), respectively. These products have been fully characterized, and the mechanism for the formation of these products is considered in the light of DFT calculations.
| Year | Citations | |
|---|---|---|
Page 1
Page 1