Table 1 Optimization of conditions for alkylation of 4-hydroxyquinazoline with acetone.

Reaction conditions: 4-hydroxyquinazoline (0.3 mmol), photocatalyst (0.003 mmol), reductant (0.6 mmol), TFA (0.6 mmol), and acetone (3.0 ml) under Ar atmosphere. The yield was determined by 1H NMR spectroscopy using dibromomethane as the internal standard. Reaction was performed in the absence of light for entry 9. Reaction was performed in the absence of photocatalyst for entry 10. Reaction was performed in the absence of TTMS for entry 11. Reaction was performed in the absence of TFA for entry 12. rt, room temperature; NR, no reaction; DIPEA, N,N-diisopropylethylamine; HEH, diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate.


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EntryPhotocatalystReductantYield (%)
1Ir[dF(CF3)ppy]2(dtbbpy)PF6TTMS96
2Ir(ppy)3TTMSNR
3[Ru(bpy)3](PF6)2TTMSNR
4Eosin-YTTMSNR
5Ir[dF(CF3)ppy]2(dtbbpy)PF6Et3SiH82
6Ir[dF(CF3)ppy]2(dtbbpy)PF6Ph3SiHNR
7Ir[dF(CF3)ppy]2(dtbbpy)PF6DIPEANR
8Ir[dF(CF3)ppy]2(dtbbpy)PF6HEH40
9Ir[dF(CF3)ppy]2(dtbbpy)PF6TTMSNR
10TTMSNR
11Ir[dF(CF3)ppy]2(dtbbpy)PF6NR
12Ir[dF(CF3)ppy]2(dtbbpy)PF6TTMSNR