Eder et al. and Hajos et al. separately reported an intramolecular asymmetric aldol reaction which employed proline as the only asymmetric catalyst at the beginning of the 1970s.¹⁾ This reaction was considered to be a special case at that time. Later in 2000, List et al. reported an intermolecular asymmetric aldol reaction which used proline as a catalyst.²⁾ List’s report received broad attention and served as a trigger to make research active for asymmetric organic catalysts. Therefore, varieties of asymmetric organic catalysts have been developed and the research has been applied to many areas.³⁾ The proline derivative 1, having the heterocyclic ring was developed by Nakamura et al. It shows high TON as an asymmetric catalyst for obtaining a chiral aldol adduct.⁴⁾

Compared with conventional metal complex catalysts, asymmetric organic catalysts are considered to be environmentally friendly and are expected to be further developed because they are stable, easy to handle and free of harmful metals.

Prolines and its analogs

Other Amino Acids

Cinchona Alkaloids

Oxazaborolidines

Chiral Phosphoric Acids

Chiral Diols

Chiral Phase-Transfer Catalysts

Other Catalysts

Prolines and its analogs

D2365	D2735	A1301
A0945	A1043	B3440
D3803	D3804	D3185
D3186	H0768	H0784
I0395	M1161	M1169
M1097	M1183	M2077
M1995	O0370	P1404
P1830	P0481	P0994
P1241	P1925	P1784
T2637	T0219

Other Amino Acids

A0177	A0179	B3398
T0228	T0230	T0539
T0541

Cinchona Alkaloids

B1683	B1689	B1684
B1685	C0347	C0348
C0349	C0350	C0351
H0752	I0728	Q0076
Q0074	Q0006	Q0010
Q0028	Q0030

Oxazaborolidines

D2130

D2131

Chiral Phosphoric Acids

B1143

B1144

Chiral Diols

B1100	B1142	B1614
B2048	B1615

Chiral Phase-Transfer Catalysts

B1683	B1689	B1684
B1685	D3475	D3476

Other Catalysts

B3296	B3549	D3983
D3984	L0137	T1215