Novel alkylation of aromatic nitriles via photo-induced electron transfer of group 14 metal-carbon σ donors

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

“…The conversion was complete after a few minutes, and readmitting air caused little change in the spectrum. Chromatographic examination confirmed the complete consumption of TCB and the formation of a single product, identified as 5-butyl-1,2,4-tricyanobenzene by comparison with an authentic sample [18]. The measured quantum yield of TCB consumption was 0.40.…”

“…The C-centered radical is not oxidized by TCB •− (see Fig. 4) but couples with it, resulting in efficient ipso-substitution of the nitrile (Φ 0.40) [18]. Thus, only path b' alone leads to the accumulation of the radical anion.…”

“…In all of the above cases, the generated radical anion (A–Y •− ) is a persistent species easily detected by laser flash photolysis. This approach applies to a variety of donors, including amines [12–13], carboxylic acids or their derivatives [14–15], aliphatic acetals and ketals [16], ethers [17], organostannanes [18–19], organosilanes [20–22], aromatics [10,23–24], and even alkanes [25–27]. BET (path a') could ensue, thus leading to no chemical change.…”

The Aromatic Carbon–Carbon ipso‐Substitution Reaction

“…In the latter case, benzyl radicals were formed from the fragmentation of either benzyltrimethylsilane or benzyltributylstannane radical cation. [28] TCB was selectively ipso-alkylated by using either group 14 metal-carbon s donors [29] or carboxylic acids [30] as the radical source (Scheme 9a,b). It is quite interesting to note that the yield of the alkyltricyanobenzene 5 was quite independent of the Bu 4 M used (74-86 %, Scheme 9a) and it was almost quantitative when using 6 as the donor.…”

Air‐Stable, Sterically Hindered Ferrocenyl Dialkylphosphines for Palladium‐Catalyzed C—C, C—N, and C—O Bond‐Forming Cross‐Couplings.

“…1 4 3 Chlorobenzene (56 mg, 0.50 mmol) reacted with phenylboronic acid (92 mg, 0.75 mmol) using 0.5/1.0 mol % of Pd(dba) 2 /Ph 5 FcP(t-Bu) 2 and KF (87 mg, 1.50 mmol) in THF solvent at 45 °C for 20 h to give the title compound (74 mg, 96%) as a white solid. 13, Entry 1): 45 Synthesis of this compound followed procedure B at 100 °C for 2.5 h. 13, Entry 2): 46 According to the procedure B at 100 °C for 30 h, 4bromoanisole was converted to the title compound as a colorless oil (132 mg, 83%): 1 13, Entry 3): 46 According to the procedure B at 100 °C for 18 h, 2chloroanisole was converted to the title compound as a colorless oil (80 mg, 94%): 13, Entry 4): 47 According to the procedure B above at 100°C for 12 h, 4-chlorobenzonitrile was converted to the title compound as a colorless oil (80 mg, 13, Entry 7): 46 According to the procedure B above using isobutyl boronic acid as reagent at 100 °C for 22 h, 4-tert-butylbromobenzne was converted to the title compound as a colorless oil (105 mg, 55%): 1 tert-Butoxybenzene (Table 14, Entry 1): 96 % yield. 1 H NMR (300 MHz, CDCl 3 ): δ 7.28 (t, 2H, J = 7.5 Hz), 7.90 (t, 1H, J = 7.5 Hz), 7.11 (d, 2H, J = 7.5 Hz), 1.37 (s, 9H).…”