Proline-derived N-sullfonylcarboxamides:: Readily available, highly enantioselective and versatile catalysts for direct aldol reactions
Proline-derived N-sullfonylcarboxamides:: Readily available, highly enantioselective and versatile catalysts for direct aldol reactions
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DOI：
10.1002/adsc.200404126
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发表时间：
2004-08-01
影响因子：
5.4
通讯作者：
Lex, J
中科院分区：
文献类型：
--
作者：
Berkessel, A;Koch, B;Lex, J
脯氨酸催化的不对称直接羟醛缩合反应涉及仲胺官能团和氨基酸的羧基。N-磺酰基酰胺类化合物具有与羧酸类似的酸性，本文合成了三种N-芳基磺酰基L-脯氨酸酰胺衍生物，作为功能化的多用途L-脯氨酸衍生物。在丙酮与对硝基苯甲醛的直接羟醛加成反应中评价了它们的催化性能。显着改善的反应性和对映体选择性，实现了在各种溶剂中，在低催化剂负载量（5-10摩尔%）和在室温下，与ee范围高达98%，而L-脯氨酸本身提供了80%的最大ee（在DMSO中）。因此，脯氨酸酰胺的N-芳基磺酰基衍生物代表了一类新型的高对映选择性催化剂用于直接羟醛缩合反应。此外，N-芳基磺酰基取代基提出了在不影响催化活性官能团的情况下并入较大催化剂组装体（包括固定化）的可能性。
Proline catalysis of the asymmetric direct aldol reaction involves both the secondary amine function and the carboxyl group of the amino acid. N-Sulfonylcarboxamides are known to be of similar acidity as carboxylic acids, and three N-arylsulfonyl derivatives Of L-proline amide were synthesized as functionalized and versatile derivatives Of L-Pro. Their catalytic performance was evaluated in the direct aldol addition of acetone to 4-nitrobenzaldehyde. Significantly improved reactivities and enantioselectivities were achieved in various solvents at low catalyst loadings (5-10 mol %) and at room temperature, with ees ranging up to 98%, whereas L-proline itself afforded a maximum ee of 80% (in DMSO). Thus, N-arylsulfonyl derivatives of proline amide represent a novel class of highly enantioselective catalysts for direct aldol reactions. Furthermore, the N-arylsulfonyl substituent suggests possibilities for incorporation into larger catalyst assemblies (including immobilization) without affecting the catalytically active functional groups.