We hereby report a major revision of the synthetic methodology for construction of the dibenzochromenone skeleton. Homophthalic acid derivatives were reacted with thionylchloride/DMF in the presence of NaN3. As the main product, dibenzochromenone derivatives were obtained. When the reaction was performed in the absence of NaN3, only isochromenones were formed. The mechanism of the formation of these
An efficient and robust methodology based on electrochemical techniques for the direct synthesis of aromatic lactones through dehydrogenative C−O cyclization is described. This new and useful electrochemical reaction can tolerate a variety of functional groups, and is scalable to 100 g under mild conditions. Remarkably, heterocycle‐containing substrates can be employed, thus expanding the scope of
The annulation of phthalides with α-alkyl/arylacrylates in the presence of LDA/LHMDS is shown to directly give alkyl/aryl-1-naphthols. The method involving a novel dealkoxycarbonylation obviates the regiochemical issues in the synthesis of polysubstituted naphthalenes, and it forms the key step in a three-step total synthesis of arnottin I, a naphthobenzopyranone natural product.
General and Practical Carboxyl-Group-Directed Remote CH Oxygenation Reactions of Arenes
作者:Yang Wang、Anton V. Gulevich、Vladimir Gevorgyan
DOI:10.1002/chem.201303511
日期:2013.11.18
Two methods for remote aromatic CHoxygenationreactions, have been developed. Method 1, the Cu‐catalyzed oxygenationreaction, is highly efficient for cyclization of electron‐neutral and electron‐rich biaryl carboxylic acids into 3,4‐benzocoumarins. Method 2, the K2S2O8‐mediated oxygenationreaction, is more general and practical for cyclization of substrates with electron‐donating and ‐withdrawing
已经开发了两种用于远程芳族 C H 氧化反应的方法。方法 1,即 Cu 催化的氧化反应,对于将电子中性和富电子的联芳基羧酸环化为 3,4-苯香豆素非常有效。方法 2,K 2 S 2 O 8介导的氧化反应,对于具有给电子和吸电子基团的底物的环化更为通用和实用(见方案)。
Cerium Ammonium Nitrate-Mediated Access to Biaryl Lactones: Substrate Scopes and Mechanism Studies
Herein we described an access to biaryl lactones from ortho-aryl benzoicacids via intramolecular O–H/C–H oxidative coupling with the commonly used ceriumammoniumnitrate (CAN) as the one-electron oxidant under a thermal condition. The radical interrupting experiment suggested a radical process, while the kinetic isotope effect (KIE) showed that the C–H cleavage likely was not involved in the rate-determining