Heterogeneous Catalysts in Pictet-Spengler-Type Reactions

Table 2

Pictet-Spengler reaction between dopamine hydrobromide and aldehydes 1 and 2.

Entry	Aldehyde	Catalyst	Yield conversion (%)^a	3/4
1	1	Acetic acid	46	97/3
2	1	B	87	82/18
3	1	Ca-B	69	88/12
4	1	H-B	32	100/0
5	1	AlPB	82	100/0
6	1	AlZrPV	63	94/6
7	1	MO	100	86/14
8	2	B	52	65/35
9	2	Ca-B	81	93/7
10	2	H-B	40	67/33
11	2	AlPB	69	97/3
12	2	AlZrPV	35	65/35
13	2	MO	84	83/17

^aCombined ¹H-NMR of 3 and 4.