Table 21.

Reaction of Brassard's diene with various aldehydes catalyzed by TADDOL B (Figure 20).

entry	Ar	toluene (mL)a	temp. (°C)	yield (%)	ee (%)
1b	Ph	0.2	−60	67	83 (S)
2b	furyl	0.2	−60	80	87 (S)
3	2-C6H4-Me	0.2	−30	54	68 (R)
4	4-C6H4-Cl	0.2	−30	85	76 (R)
5	4-C6H4-Br	0.2	−30	72	78 (R)
6	3-C6H4-Br	0.2	−60	67	89 (R)
7	2-C6H4-Br	0.2	−60	75	82 (R)
8	3-C6H4-OMe	0.2	−60	45	91 (n.d.)

^aAll the reactions were carried out with 2.5 mmol of benzaldehyde and 0.5 mmol of diene.

^bThe catalyst employed in this case was (R,R)-B.