Palladium‐Catalyzed Cross‐Coupling Reactions in Total Synthesis

Abstract

In studying the evolution of organic chemistry and grasping its essence, one comes quickly to the conclusion that no other type of reaction plays as large a role in shaping this domain of science than carbon-carbon bond-forming reactions. The Grignard, Diels-Alder, and Wittig reactions are but three prominent examples of such processes, and are among those which have undeniably exercised decisive roles in the last century in the emergence of chemical synthesis as we know it today. In the last quarter of the 20th century, a new family of carbon-carbon bond-forming reactions based on transition-metal catalysts evolved as powerful tools in synthesis. Among them, the palladium-catalyzed cross-coupling reactions are the most prominent. In this Review, highlights of a number of selected syntheses are discussed. The examples chosen demonstrate the enormous power of these processes in the art of total synthesis and underscore their future potential in chemical synthesis.

Shape‐Switchable Azo‐Macrocycles

“…[191]- [194] The solvent was changed from the reported toluene to a more polar and protic solvent mixture of toluene with ethanol. This solvent mixture resulted in a significant 20% increase in the yield.…”

“…[191] Treatment of 2.6 equivalents of the commercially available 3-nitrophenyl-boronic acid (35) The first purification step was a column chromatography with silica gel and dichloromethane, the obtained crude product was further purified by different preparative thin layer chromatography techniques, the use of n-hexane instead of cyclohexane and the use of 0.5 mm prep TLC plates instead of 2.0 mm prep TLC plates, respectively, turned out to be crucial for the purification. The separated bands of the chromatography were analyzed be MALDI-TOF mass spectrometry to determine the molecular weight; this purification procedure was repeated until the pure macrocyclic compound was isolated.…”

“…[191] [192][194] [224] As it was a key reaction in the assembly of all target semicircles 11, 16, 32 and 43, the mechanism including the catalytic cycle is shown in Scheme 24 and will be briefly discussed. [24] [207] The coupling takes place between an organoboronic acid and aryl halides.…”

Recent Applications of the Suzuki-Miyaura Cross-coupling to Complex Polycyclic Ether Synthesis

“…11 Among them, the palladium catalyzed Suzuki Miyaura coupling reaction has been one of the most useful and reliable carbon carbon bond forming reactions in organic synthesis. 12 This reaction has several signi cant advantages over other cross coupling reactions; most notably, it is capable of generating a C(sp 3 ) C(sp 2 ) bond.…”

A reação de Diels-Alder no início do século vinte um

“…É digno de nota que as reações pericíclicas em geral, e certamente as cicloadições [4+2], as reações de Diels-Alder, não precisam de grupos protetores para a sua perfeita execução (conceito de Baran), 9 ocorrem com total economia de átomos (conceito de Trost), 10 apresentam um aumento considerável de complexidade estrutural (conceito de Wender) 11 e com a criação de duas ligações σ novas são altamente construtivas (conceito de Hendrickson). 12 Atualmente, a reação de Diels-Alder compete com as reações de metátese 13,14 e acoplamento cruzado 15 como as reações chaves em síntese total, frequentemente em parceria ou até em combinação dominó. 16,17 Outro aspecto novo se refere à abordagem dada à reação de DielsAlder em livros textos.…”