Table 1.

Evaluation of the Catalytic Activities of PPTS Lipid Analogues (Figure 1) using an Esterification Reaction of 4-Phenylbutyric Acid with 1-Octanol^a

entry	catalyst	yield of ester (%)b
1	PPTS (1)	n.d.c
2	2	n.d.
3	3	16
4	4	48
5	5	49
6	6	76/99d
7	7	n.d.
8	8	n.d.
9	9	n.d.

^aConditions: 4-phenylbutyric acid (2 mmol), 1-octanol (2 mmol), and catalyst (5 mol%) in isooctane (4 mL) at 25 °C for 72 h.

^bDetermined by GC analysis.

^cNot detected by GC experiments.

^dThe yield of 76% at 25 °C and 99% at 80 °C, respectively.