Synthesis of Phenols via Metal-Free Hydroxylation of Aryl Boronic Acids with Aqueous TBHP

Table 1

Solvent study: hydroxylation of phenylboronic acid^a.

Entry	Solvent	Temp. (°C)	Time (h)	Yield (%)^b,c
1	THF	0	1	NR
2	THF	25	1	Trace
3	THF : H2O	25	1	22
4	CH3CN : H2O	25	3	10
5	DMF : H2O	70	3	>5^d
6	THF : H2O	50	3	25
7	H2O	25	1	18
8	H2O	70	3	47

^aReaction conditions: phenylboronic acid (1 mmol), aqueous TBHP (1 mmol), Cs₂CO₃ (0.5 mmol), and solvent stirred at designated temperature and time; ^bisolated yield; ^cproducts were characterized by MP, FTIR, and 1H- and 13C-NMR; ^dtraces of the product when CH₃CN and pyridine solvents were used.