Dihydroxyacetone Variants in the Organocatalytic Construction of Carbohydrates: Mimicking Tagatose and Fuculose Aldolases
摘要:
Dihydroxyacetone variants have been explored as donors in organocatalytic aldol reactions with various aldehyde and ketone acceptors. The protected form of dihydroxyacetone that was chosen for in-depth study was 2,2-dimethyl-1,3-dioxan-5-one, 1. Among the catalysts surveyed here, proline proved to be superior in terms of yield and stereoselectivities in the construction of various carbohydrate scaffolds. In a fashion analogous to aldolase enzymes, the de novo preparation of L-ribulose, L-lyxose, D-ribose, D-tagatose, 1-amino-1-deoxy-D-lyxitol, and other carbohydrates was accomplished via the use of 1 and proline. In reactions using 2,2-dimethyl-1,3-dioxan-5-one 1 as a donor, (S)-proline can be used as a functional mimic of tagatose aldolase, whereas (R)-proline can be regarded as an organocatalytic mimic of fuculose aldolase.
Direct asymmetric organocatalytic de novo synthesis of carbohydrates
作者:Christoph Grondal、Dieter Enders
DOI:10.1016/j.tet.2005.09.060
日期:2006.1
A biomimetic organocatalytic asymmetric synthesis of carbohydrates can be accomplished by a proline catalyzed aldol reaction with the dihydroxyacetone equivalent 2,2-dimethyl-1,3-dioxan-5-one and various aldehydes. The biomimetic C3+Cn strategy directly generates selectively protected carbohydrates in one step, which can be easily deprotected. Additionally, the stereoselective reduction of the keto
碳水化合物的仿生有机催化不对称合成可以通过脯氨酸催化的羟醛反应与二羟基丙酮当量的2,2-二甲基-1,3-二恶烷-5-酮和各种醛反应来完成。仿生C 3 + C n策略可在一个步骤中直接生成选择性保护的碳水化合物,可以很容易地对其进行脱保护。另外,酮基功能的立体选择性降低允许直接进入不同的醛糖。