Table 1.

Rate constants for the benzoin condensation.^a

Thiazolium Coenzyme Mimics (14)
Entry	R1	R2	X	PEI	V (×10−9 M/s)	krelb
1c	C12H25	BnO	Br	-	4	1
2	C12H25	BnO	Br	11	5040 ± 60	1260 ± 15
3	C12H25	BnO	Br	13	5136 ± 111	1284 ± 28
4d	C12H25	BnO	Br	11	5167 ± 222	1304 ± 56
5	C12H25	BnO	I	11	4944 ± 111	1248 ± 28
6	Bn	BnO	Cl	11	24 ± 2	6 ± 0.5
7	Me	C12H25S	I	11	552 ± 56	138 ± 14
8	C4H9	C12H25S	I	11	9424 ± 524	2356 ± 131
9	C6H13	C12H25S	I	11	4664 ± 40	1166 ± 10
10	Bn	C12H25S	Br	11	1552 ± 16	388 ± 4
11	C4H9	C12H25S	I	12	596 ± 16	149 ± 4
Imidazolium Coenzyme Mimics (4)
Entry	R	X	PEI		V (×10−9 M/s)	krelb
12	Me	I	-		0.36	1
13	C4H9	I	13		13 ± 0.17	37 ± 0.5
14	C6H13	I	13		18.7 ± 0.33	52 ± 1
15	C8H17	I	13		44 ± 2	123 ± 6
16	C10H21	I	13		833 ± 11	2314 ± 31
17	C12H25	I	13		1225 ± 3	3402 ± 8
18	C12H25	I	11		83 ± 5	230 ± 14

^(a)Coenzyme loading = 10 mol % (14), 40 mol % (4); [PEI] = 6 mM; [PhCHO]_initial = 40mM.

^(b)Relative to entry 1 or 12, respectively. Errors are the deviations from two runs.

^(c)One run.

^(d)Buffer concentration = 0.2M Na₂HPO₄ (pH~8.0).

^(e)Calculated from the initial slope of [Benzoin] vs. time. Errors are the deviations from two runs.