生物质糖催化转化过程中手性结构的保留和重建

Biomass resource containing rich carbohydrate is the only alternative carbon sources for the construction of chemicals and materials for human survival in the future. Biomass is characterized by natural chemical structure and chirality so that it may offer completely different pathway and features of catalytic conversion compared with fossil resource, which will provide a platform and opportunity for the design of new catalytic systems and materials. The project proposes to achieve retainment and regeneration of chiral structure during catalytic transformation of biomass-derived sugars, and develop new catalytic system and technological route of biomass-derived sugars converted towards new chiral platform molecules. To solve the poor stability of products tetroses/trioses, this project will design and screen the optimum catalyst of retro-adol condensation of sugars, structure stabilizer as well as reaction condition, and guarantee the well retainment of their chiral structure. This project also break the barrier between chemical and enzymatic catalysis, and develop compatible chemical-enzymatic catalytic system to carry out the one-pot regeneration of chiral structure during the sugar conversion. Meanwhile, a full understanding of key scientific issues between the new catalytic system and a series of competition reactions such as isomerization, C-C bond cracking and intramolecular hydrogen shift as well as the cooperation of chemical-enzymatic catalysis and their performances will be formed. These will help to improve values of biomass transformation and its competitiveness compared with fossil resource.

含有丰富碳水化合物的生物质资源是未来人类生存所依赖化学品和材料制备的唯一可再生碳源。碳水化合物特有的天然化学结构和单一手性特点，使其可能具有不同于化石资源的催化转化途径和特色，这为新催化体系的设计提供了平台和机遇。项目以碳水化合物催化转化过程中手性结构的保留和重建为目标，发展从生物质糖催化转化制备新的手性平台化合物的新催化体系和技术路线。项目针对低碳糖稳定性差的缺点，重点通过Lewis催化剂设计与合成、稳定剂协同与匹配、反应条件的控制与优化，确保糖催化转化过程中手性结构的保留，发展新的手性平台化合物；也将着重发展兼容的酶-化学催化体系，打通酶催化与上游生物质糖化学催化之间的壁垒，实现对高附加值生物质平台化合物的手性one-pot重建。最终形成对新催化体系与序列竞争（异构、C-C断裂、分子内氢转移）反应以及化学-酶催化活性匹配与性能关系的科学认识，提高生物质碳源与现有化石资源的竞争力。

碳水化合物特有的天然化学结构和单一手性特点，使其可能具有不同于化石资源的催化转化途径和特色，这为探索生物质资源区别于石化资源利用的催化体系设计提供了想象空间和难得的机遇。本项目以C6醛糖为底物，发展了三种制备D-(-)-赤藓糖的催化转化路线，成功打通了从生物质糖到C4手性合成子的反应路径；利用生物质自身的优缺点，发展了由生物质糖出发制备糖醇、羟基酸以及手性酯的系列新催化转化路线，拓展了生物质平台化合物产物链并最大可能提高了生物质化合物的原子利用率；随着对生物质催化转化过程的深入理解，本项目还以生物质平台化合物为底物，发展了氢转移反应、Aldol缩合、醚化等系列反应相结合的生物质高效升级转化路线。这些全新反应路线的开发无疑为生物质平台化合物到高附加值中间体化学品的转化提供了依据和新思路，也为手性化合物以及H2的制备提供了新视角。