Synthesis of Chelocardin, Amidochelocardin, Premithramycinon and Chromocyclin

该项目的目的是建立chelocardin（2），guaramidochelocardin（3），premithramycinon（5）和chromocyclin（6/7）的合成途径。这些天然产物的特征在于共同的主链，其与已建立的四环素的不同仅在于C2处存在甲基酮，以及C4处的不同构型。在普瑞霉素（5）和色环素（6/7）的情况下，在位置4处存在醇部分而不是胺。所有天然产物都表现出不同的生物活性，因此是医学应用的宝贵起点。作为我们正在进行的计划的一部分，合理化天然产品的生物活性，由于微妙的结构变化，我们首先需要获得这些化合物，并有可能改变我们的意愿的结构。如此获得的化合物随后将用于目标鉴定研究。然而，该项目的目标是建立对上述天然产品的合成获取。

The aim of this project is to establish synthetic access to chelocardin (2), carbamidochelocardin (3), premithramycinon (5) and chromocyclin (6/7). These natural products are characterized by a common backbone, which differs from established tetracyclins only due to the presence of a methyl ketone at C2, and a different configuration at C4. In the case of premithramycinon (5) and chromocyclin (6/7) at position 4 there is an alcohol moiety instead of the amine. All natural products exhibit different biological activities and are therefore valuable starting points for medical applications. As part of our ongoing program to rationalize the biological activities of natural products due to subtle structural changes, we firstly need access to these compounds and the possibility to alter the structures at our will. The so-obtained compounds will afterwards being used for target identification studies. However, the goal of this project is to establish synthetic access to the above mentioned natural products.