Kano Taichi, Yamaguchi Yukako, Maruoka Keiji
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
Chemistry. 2009 Jul 6;15(27):6678-87. doi: 10.1002/chem.200900267.
A direct asymmetric Mannich reaction using a novel axially chiral amino sulfonamide (S)-3 that is highly anti- and enantioselective has been developed. For instance, in the presence of a catalytic amount of (S)-3, the reactions between aldehydes and alpha-imino esters proceeded smoothly to give anti Mannich products with a significantly higher anti/syn ratio and enantioselectivity than previously possible. By utilizing N-Boc-protected aromatic imines instead of alpha-imino esters, the synthetically useful Boc protecting group and various aromatic or heteroaromatic substituents were installed into the anti Mannich products and consequently the substrate scope of the anti-selective Mannich reaction and the synthetic utility of the anti Mannich products have been expanded. The axially chiral amino sulfonamide (S)-3 has also been successfully applied to asymmetric direct cross-aldol reaction between two different aldehydes. The catalyst (S)-3 has the advantage of giving mainly syn products, whereas proline shows the opposite anti selectivity.
已开发出一种使用新型轴向手性氨基磺酰胺(S)-3的直接不对称曼尼希反应,该反应具有高度的反式选择性和对映选择性。例如,在催化量的(S)-3存在下,醛与α-亚氨基酯之间的反应顺利进行,得到反式曼尼希产物,其反式/顺式比例和对映选择性比以前更高。通过使用N-Boc保护的芳香族亚胺代替α-亚氨基酯,将具有合成用途的Boc保护基和各种芳香族或杂芳香族取代基引入反式曼尼希产物中,从而扩大了反式选择性曼尼希反应的底物范围和反式曼尼希产物的合成效用。轴向手性氨基磺酰胺(S)-3也已成功应用于两种不同醛之间的不对称直接交叉羟醛反应。催化剂(S)-3的优点是主要生成顺式产物,而脯氨酸则表现出相反的反式选择性。