A simple and eco-sustainable method for the O-Boc protection/deprotection of various phenolic structures under water-mediated/catalyst-free conditions

Figures & data

Table 1. Evaluation of different solvents for O-Boc protection of phenol under catalyst-free conditions.

Solvents	Time (h)	Yield (%)
H2O	0.75	95
MeOH	72	10
EtOH	72	4
MeCN	72	0
THF	72	0
CH3Cl	72	0
CCl4	72	0

short-legendScheme 1. Water-mediated chemoselective O-tert-butoxycarbonylation of phenol.

Table 2. O-Boc protection/deprotection of hydroxy compounds.

			O-Boc protection^a	O-Boc deprotection^b
Entry	Substrate	Product	T (min)/yield (%)	T (min)/yield (%)
1			45/95	8/98
2			30/87	3/95
3			70/96	5/100
4			55/90	8/90
5			90/93	10/89
6			120/85	10/98
7			90/90	6/97
8			65/97	6/99
9			70/95	2/100
10			50/90	3/100
11		–	–/–	–/–
12		–	–/–	–/–
^a1 mmol of substrate was treated with 1 mmol of (Boc)2O in 5 mL (9.5/0.5) of (water:acetone) under neat at room temperature.
^bAll reactions were carried out in depressurized systems under argon atmosphere; 1 mmol of substrate was dissolved in 10 mL of freshly bidistilled water.

short-legendScheme 2. O-tert-butoxycarbonylation of bisubstituted phenol.