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. Author manuscript; available in PMC: 2009 Nov 13.
Published in final edited form as: Tetrahedron Lett. 2009 May 13;50(19):2252–2255. doi: 10.1016/j.tetlet.2009.02.210

Table 2.

Enantioselective two-component reaction for the synthesis of pyranopyrazoles with catalyst 2a

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Entry Compound R1 R2 R3 Time (h) Yieldb (%) eec (%)
1 12a Me H H 27 92 96
2 12b Me F H 7.5 96 58
3d 12c Me Cl H 11 95 62
4 12d Me Br H 8 89 50
5d 12e Me I H 11 94 48
6 12f Me CN H 15 92 40
7 12g Me NO2 H 14 88 36
8 12h Me Me H 15 96 20
9 12i Me OMe H 20 96 36
10 12j Me H Br 14 92 26
11 12k Et H H 12 84 38
12 12l Ph H H 17 89 48
13e 12m Me 19 79 28
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a

Unless otherwise indicated, all reactions were carried out with 10a (0.10 mmol), 11a (0.10 mmol), and the catalyst (5 mol %) in CH2Cl2 (2.0 mL) at rt.

b

Yield of isolated product after chromatography.

c

Determined by HPLC analysis on a ChiralPak AS column.

d

Carried out at 0 °C.

e

Determined by HPLC analysis on a ChiralPak AD-H column.