Microwave-Accelerated Selective Acylation of (Hydroxyalkyl)phenols Using Acid Chlorides

Figures & data

Figure 1 (Hydroxyalkyl)phenols examined in this study.

Table 1. Acetylation of 2-(4-hydroxyphenyl)ethanol () using acetyl chloride in the absence or presence of an additive in tetrahydrofuran under conventional heating (Δ) or microwave irradiation (MW) ^a

				Products (%)
Entry	Additive ^b	Mode	Time (min)	1f	1g	1h
1	None	Δ	40	40.7	0	0
2	None	MW	40	83.6	0	7.4
3	Pyridine	Δ	40	81.0	0	19.0
4	Pyridine	MW	40	66.6	0	33.3
5	Et3N	Δ	40	0	30.0	70.0
6	Et3N	MW	40	0	31.0	69.0

Table 2. Acylation of (hydroxyalkyl)phenols using acid chlorides in tetrahydrofuran under conventional heating (Δ) or microwave irradiation (MW) ^a

				Products (%)
Entry	Starting diol	Mode	Time (min)	Alkyl ester	Phenyl ester	Diester
1	1e ^b	Δ	40	1f, 19.4	1g, 0	1h, 0
2	1e ^b	MW	40	1f, 31.8	1g, 0	1h, 0
3	1e ^c	Δ	40	1f, 37.7	1g, 0	1h, 0
4	1e	MW	40	1f, 68.4	1g, 0	1h, trace
5	1e ^c	Δ	60	1f, 38.6	1g, 0	1h, 0
6	1e	MW	60	1f, 94.0	1g, 0	1h, 6.0
7	1e ^d	Δ	60	1i, 21.4	1j, 0	1k, 0
8	1e ^d	MW	60	1i, 89.6	1j, 0	1k, 2.8
9	1a	Δ	10	1b, 29.9	1c, 0	1d, 0
10	1a	MW	10	1b,100	1c, 0	1d, 0
11	1l	Δ	20	1m, 23.3	1n, 0	1o, 0
12	1l	MW	20	1m, 94.5	1n, 0	1o, 5.5
13	2a	Δ	30	2b, 62.2	2c, 0	2d, 0
14	2a	MW	30	2b, 100	2c, 0	2d, 0
15	3a	Δ	40	3b, 32.6	3c, 0	3d, 0
16	3a	MW	40	3b, 98.1	3c, 0	3d, 1.9
17	4a	Δ	30	4b, 43.4	4c, 0	4d, 0
18	4a	MW	30	4b, 100	4c, 0	4d, 0