Table 1.

Optimization of the reaction conditions for the Friedel–Crafts Michael-type reaction.[a]

Entry	Solvent [mL]	t [h]	Yield [%][b]	ee [%][c]
1	CHCl3 (1.5)	16	56	91
2	CH2Cl2 (1.5)	15	59	87
3	toluene (1.5)	21	60	88
4	PhCl (1.5)	21	61	87
5	toluene (3.0)	21	70	91
6	CH2Cl2 (3.0)	24	68	91
7[d]	CHCl3 (3.0)	65	89	93
8[d]	toluene (3.0)	65	95	93

[a] General reaction conditions: 2 a (0.5 mmol), pyrrole 1 a (1.0 mmol), 10 (20 mol %), TFA (30 mol %), rt. [b] Yield of isolated 3. [c] Determined by HPLC analysis on a chiral stationary phase. [d] The reaction was performed at 0 °C.