Palladium/Norbornene Catalyzed Decarbonylative Alkynylation And Cleavage Of C(O)-S Bond

Catellani reaction is a domino reaction that catalyzed by palladium/norbornene. The capacity to functionalize both the ortho and ipso positions of aryl halides in a single transformation makes it useful in the synthesis of poly-substituted aromatic compounds. Since its development in 1997, various poly-functionalized arenes have been synthesized, particularly the contributions from the groups of Lautens and Catellani. In this paper, alkynyl carboxylic acids and 1,1-dimethyl-2-alkynol were successfully applied to the Catellani reaction as quenching reagents. Besides, We also presented a Pd/norbornene/Cu-cooperatively-catalyzed reaction which is useful in the efficient synthesis of α-keto diaryl sulfides from aryl halides and thioesters This paper mainly includes the following four chapters:Chapter one:the development of the Catellani reaction.In this chapter, we briefly describe the application of different quenching reagents and new types of electrophiles used in the Catellani reaction. The application of this reaction in the total synthesis is also included in this chapter.Chapter two:Decarboxylative Alkynyl Termination of Catellani reactionThis chapter introduces that we successfully used the N-benzoyloxyamines as electrophiles and alkynyl carboxylic acids as alkynyl termination reagents in the Catellani reaction afforded α-Alkynyl Anilines with moderate to excellent yields. Compared with the previous method, this approach showed simple operation and excellent substrate generality.Chapter three:Decarbonylation Alkynyl Termination of Catellani reactionDecarboxylative alkynylation strategy was only successful for the synthesis of 2-alkynylanilines. However, when alkyl iodide instead of O-benzoyl hydroxylamine was used, the major side reaction was the esterification of carboxylic acid with the alkyl iodides. The use of 1,1-dimethyl-2-alkynols as alkynyl reagents not only matched the reactivity with other components, but also substantially inhibited the side-reaction of O-alkylation. Different from decarboxylative alkynylation, alkynol with electron-withdrawing groups on the benzene ring can also successfully participate in the reaction. This reaction shows excellent functional group tolerance.Chapter four:Pd/norbornene/Cu-cooperatively-catalyzed C(O)-S bond cleavage of thioestersWith Pd/norbornene/Cu-cooperative catalysis, we realized a ortno C-H acylation and ipso-thiolation reaction of aryl halides by the cleavage of C(O)-S bond of thioesters which afforded a series of a-keto diaryl sulfides in moderate to good yields. The regioselectivity of the product was unambiguously confirmed by the single crystal X-ray analysis. The reaction performed in an atom-economic way, where both the acyl and thiol groups were incorporated into the aryl ring. CuⅠ played a key role in the reaction, meanwhile, it demonstrates the first example in the palladium/norbornene catalysis that Lewis acid (CuX) assists the oxidative addition of palladacycle PdⅡ with electrophiles.