Nickel-Catalyzed Reductive 1,2-Dialkynylation of Alkenes Bearing an 8-Aminoquinoline Directing Group
摘要:
An unprecedented nickel-catalyzed reductive 1,2-dialkynylation of alkenes bearing an 8-aminoquinoline directing group has been developed. This method proceeded through a migratory insertion/reductive-coupling process under mild conditions with a wide substrate scope and good functional group tolerance, providing direct access to the synthetically flexible 1,5-diynes. Moreover, the 1,2-dialkynylation products could be further converted to borate-ester- or azide-functionalized 1,5-dienes, ditriazole, beta-diyne primary amide, and trisubstituted benzene.
Alkyne Versus Ynamide Reactivity: Regioselective Radical Cyclization of Yne‐Ynamides
作者:Shubham Dutta、Rajendra K. Mallick、Rangu Prasad、Vincent Gandon、Akhila K. Sahoo
DOI:10.1002/anie.201811947
日期:2019.2.18
Ynamides are typically more reactive than simple alkynes and olefins. However, a serendipitous observation revealed a rare case where the reactivity of simple alkynes exceeds that of ynamides. This led to the development of a unique sulfur‐radical‐triggered cyclization of yne‐tethered ynamides, which involves attack of the alkyne by a thiyl radical followed by cyclization with the ynamide. A wide range
Iron(II) Halide Promoted Cyclization of Cyclic 2-Enynamides: Stereoselective Synthesis of Halogenated Bicyclic γ-Lactams
作者:Ming-Chang P. Yeh、Yuan-Shin Shiue、Hsin-Hui Lin、Tzu-Yu Yu、Ting-Chia Hu、Jia-Jyun Hong
DOI:10.1021/acs.orglett.6b00916
日期:2016.5.20
A simple and mild process was developed for the highly stereoselectivesynthesis of halogenated bicyclic [4.3.0] and [3.3.0] γ-lactams, possessing four stereocenters, from easily available cyclic 2-enynamides. The reaction required only an inexpensive iron(II) halide under dry air and was tolerant of aryl, heteroaryl, and alkyl groups at the alkyne terminus.
Synthesis of Spirolactams and Fused Bicyclic Lactams via Acid-Promoted Cyclolactamization of (Ethynyl(tosyl)amino)methyl-Tethered Cyclohex-2-enols
作者:Po-Ting Tung、Chang-Zhi Zhong、Tzu-Chiang Chien、Ming-Chang P. Yeh
DOI:10.1021/acs.joc.7b02158
日期:2017.11.3
keteniminium–allylic carbocation intermediate. Hydration of the keteniminium ion, followed by attack of the resulting enolate onto the tethered allylic carbocation, provided the spirolactam ring skeleton. This strategy could also be employed in the synthesis of fused bicyclic lactams from BF3·OEt2-assisted cyclolactamization of TBS-protected 2-(ethynyl(tosyl)amino)methylcyclohex-2-enols.
Regioselective Synthesis of 2,4,5-Trisubstituted Oxazoles and Ketene Aminals via Hydroamidation and Iodo-Imidation of Ynamides
作者:Rajendra K. Mallick、B. Prabagar、Akhila K. Sahoo
DOI:10.1021/acs.joc.7b02124
日期:2017.10.6
A novel and straightforward protocol is demonstrated for the synthesis of highly substituted oxazoles from readily accessible ynamides in the presence of ytterbium(III) trifluoromethanesulfonate [Yb(OTf)3], N-iodosuccinimide (NIS), and acetonitrile. Multiple oxazole skeletons in the aryl periphery are constructed in a single operation for the first time. The hydroamidation and iodo-imidation of ynamides