nucleophilic ring opening induced by an Rh‐bound nitrenegenerated in situ, details of which were uncovered by both experimental and theoretical studies. In particular, DFT calculations show that the nitrogen atom of the putative [Rh]2=NR metallanitrene intermediate is electrophilic and support an aziridine activation pathway by N⋅⋅⋅N=[Rh]2 bond formation, in addition to the N⋅⋅⋅[Rh]2=NR coordination mode.
Palladium- and Ruthenium-Catalyzed Cycloisomerization of Enynamides and Enynhydrazides: A Rapid Approach to Diverse Azacyclic Frameworks
作者:P. Ross Walker、Craig D. Campbell、Abid Suleman、Greg Carr、Edward A. Anderson
DOI:10.1002/anie.201304186
日期:2013.8.26
I want to ride my azacycle: The title reaction of enynamides affords a wide diversity of azacycles. The reactions are high‐yielding, highly stereoselective, and proceed rapidly under mild reaction conditions. Equivalent transformations using enynhydrazides offer new routes to pyrazole and indazole scaffolds. Boc=tert‐butoxycarbonyl, EWG=electron‐withdrawing group, Ns=4‐nitrobenzenesulfonyl, Ts=4‐toluenesulfonyl
Carbamoyl radicals from Se-phenylselenocarbamates: Intramolecular additions to alkenes
作者:James H. Rigby、Diana M. Danca、John H. Horner
DOI:10.1016/s0040-4039(98)01830-9
日期:1998.11
A series of 5 exo-trig cyclizations of carbamoyl radicals generated from readily available Se-phenylselenocarbamates is reported. Kinetic studies indicate that the rate constant of this cyclization exceeds 1×108s−1 in reveral cases.
据报道,由容易获得的Se-苯基硒代氨基甲酸酯产生的氨基甲酰基自由基有5个exo- trig环化作用。动力学研究表明,在复性情况下,该环化的速率常数超过1×10 8 s -1。
Gold- and Silver-Catalyzed Tandem Amination/Ring Expansion of Cyclopropyl Methanols with Sulfonamides as an Expedient Route to Pyrrolidines
作者:Weidong Rao、Philip Wai Hong Chan
DOI:10.1002/chem.200801242
日期:2008.11.17
An efficient syntheticroute to pyrrolidines that relies on AuCl/AgOTf-catalyzed tandem amination/ringexpansion of substituted cyclopropyl methanols with sulfonamides is reported herein. The reactions proceed rapidly at 100 degrees C with catalyst loadings as low as 2 mol % and produce the pyrrolidine products in yields of 30-95 %. The method was shown to be applicable to a broad range of cyclopropyl
Copper‐Catalyzed Azide–Ynamide Cyclization to Generate α‐Imino Copper Carbenes: Divergent and Enantioselective Access to Polycyclic N‐Heterocycles
作者:Xin Liu、Ze‐Shu Wang、Tong‐Yi Zhai、Chen Luo、Yi‐Ping Zhang、Yang‐Bo Chen、Chao Deng、Rai‐Shung Liu、Long‐Wu Ye
DOI:10.1002/anie.202007206
日期:2020.10.5
Here an efficient copper‐catalyzed cascade cyclization of azide‐ynamides via α‐imino copper carbene intermediates is reported, representing the first generation of α‐imino copper carbenes from alkynes. This protocol enables the practical and divergent synthesis of an array of polycyclic N‐heterocycles in generally good to excellent yields with broad substrate scope and excellent diastereoselectivities