The Pd‐catalyzed reaction between 2,2′‐dibromobiphenyls and related systems with tosylhydrazones gives rise to new π‐extendedconjugatedpolycarbo‐ and heterocyclesthrough an autotandem process involving a cross‐coupling reaction followed by an intramolecular Heck cyclization. The reaction shows wide scope regarding both coupling partners. Cyclic and acyclic tosylhydrazones can participate in the
Rhodium(II)-Catalyzed Cyclization of Bis(N-tosylhydrazone)s: An Efficient Approach towards Polycyclic Aromatic Compounds
作者:Ying Xia、Zhenxing Liu、Qing Xiao、Peiyuan Qu、Rui Ge、Yan Zhang、Jianbo Wang
DOI:10.1002/anie.201201374
日期:2012.6.4
Ahead of the PAC: Polycyclicaromaticcompounds (PACs) can be easily accessed by the combination of Suzuki–Miyaura cross‐coupling and a [Rh2(OAc)4]‐catalyzed carbene reaction using easily available bis(N‐tosylhydrazone)s as intermediates (see scheme; Ts=4‐toluenesulfonyl).
arylmagnesium bromides with TiCl4 affords the corresponding symmetric biaryls in moderate to good yields at 0°C or lower. Tributylmagnesate-induced halogen–magnesium exchange of aryl halides followed by the coupling reaction provides biaryls in good yields under mild conditions. This method can achieve a one-pot synthesis of biaryls containing functional groups such as esters, amides, or nitriles.
Pd-Catalyzed Autotandem C–C/C–C Bond-Forming Reactions with Tosylhydrazones: Synthesis of Spirocycles with Extended π-Conjugation
作者:Raquel Barroso、Rocío A. Valencia、María-Paz Cabal、Carlos Valdés
DOI:10.1021/ol500778u
日期:2014.4.18
A new Pd-catalyzed autotandem process is presented by the reaction of tosylhydrazones of cyclic ketones and 2,2′-dibromobiphenyls and related systems. The process involves cross-coupling with tosylhydrazone followed by an intramolecular Heck reaction and gives rise to spirocyclic structures. Noteworthy, two C–CAr bonds are formed on the hydrazonic carbon during the process. Depending on the starting
Halogen–lithium exchange versus deprotonation: synthesis of diboronic acids derived from aryl–benzyl ethers
作者:Tomasz Kliś、Janusz Serwatowski
DOI:10.1016/j.tetlet.2006.12.076
日期:2007.2
Lithiation of a series of aryl benzyl ethers containing halogen substituents (–F, –Br, –I) was investigated. The resultant mono- and diorganolithium intermediates were converted into the corresponding aldehydes or diboronic acids in good yields. The dilithiation of aryl benzyl ethers containing a reactive hydrogen atom and halogenatom capable of halogen–lithium exchange proceeds quantitatively in