Biomimetic carbene catalyzed oxidative activation of aldehydes

仿生卡宾催化醛的氧化活化

• 批准号: 121180819
• 负责人: Professor Dr. Armido Studer
• 金额: --
• 依托单位: Organisch-Chemisches Institut
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/121180819?language=en
• 关键词: Biomimetic; carbene; catalyzed; oxidative; activation

Carbenes have been intensively used as catalysts for the umpolung of aldehydes. The well investigated benzoin condensation and the Strecker reaction are prominent examples. In these processes the carbene catalyst is used to intermediately generate the so called Breslow intermediate which further reacts in an ionic process with an aldehyde, with an activated electron-poor double bond or with other electrophiles. More recently, leaving groups at the -position of the Breslow intermediate have been installed to transfer the enol ether into an activated acylcarbenium ion. Most of the carbene-catalyzed transformations of aldehydes deal with ionic transformations of the Breslow intermediate. In the proposal we use single electron transfer oxidation reagents for the formation of activated acylcarbenium ions in biomimetic processes. This type of carbene catalysis also used by nature is not well investigated so far in synthesis. Among dioxygen other environmentally benign single electron transfer oxidants in particular nitroxides will be tested. Metal based oxidants will be avoided in these organocatalyzed reactions. Activation of ,-unsaturated aldehydes will generate activated Michael acceptors which should undergo 1,4-addition reactions. We plan to study stereoselective intramolecular 1,4-additions of alcohols, protected amines and thiols via carbene catalyzed redox activations. Moreover, acylcarbenium ions will also be used in intramolecular transition metal free aldehyde C-H-activation reactions for the formation of cyclic ketones.

卡宾斯已被强烈用作醛的Umpolung的催化剂。经过良好研究的苯并凝结和Strecker反应是突出的例子。在这些过程中，碳烯催化剂用于中间生成所谓的布雷斯洛中间体，该中间体在离子过程中与醛一起进一步反应，并具有活化的电子贫血双键或其他电力。最近，已经安装了布雷斯洛中间体的位置的组以将烯醇醚转移到活化的酰基碳酸离子中。醛的大多数碳烯催化转化都涉及布雷斯洛中间体的离子转化。在提案中，我们使用单电子转移氧化试剂在仿生过程中形成活化的酰基碳酸离子。到目前为止，这种类型的卡宾催化剂在合成中还没有很好地研究。在二氧化物中，将测试其他环境良性单电子转移氧化物，特别是氮氧化物。在这些有机催化反应中，将避免使用金属的氧化物。 的激活，不饱和醛的激活将产生活化的迈克尔受体，应经历1,4个吸收反应。我们计划通过卡宾催化的氧化还原活化研究立体选择性分子内1,4个醇，保护胺和硫醇。此外，酰基碳酸离子也将用于分子内过渡金属无醛C-H激活反应，以形成环状酮。