Ti-Catalyzed Multicomponent Oxidative Carboamination of Alkynes with Alkenes and Diazenes
作者:Zachary W. Davis-Gilbert、Letitia J. Yao、Ian A. Tonks
DOI:10.1021/jacs.6b09939
日期:2016.11.9
The inter- or intramolecular oxidative carboamination of alkynes catalyzed by [py2TiCl2NPh]2 is reported. These multicomponent reactions couple alkenes, alkynes and diazenes to form either α,β-unsaturated imines or α-(iminomethyl)cyclopropanes via a TiII/TiIV redox cycle. Each of these products is formed from a common azatitanacyclohexene intermediate that undergoes either β-H elimination or α,γ-coupling
REGIOSELECTIVE 1,5-ENYNE SYNTHESIS FROM ORGANOBORANES
作者:Shoji Hara、Yoshitaka Satoh、Akira Suzuki
DOI:10.1246/cl.1982.1289
日期:1982.8.5
2-Alkynylboranes prepared from 2-propynyl chloride and trialkylboranes react readily with allylic halides in the presence of cuprous iodide to give 1,5-enynes regioselectively.
α-Diimine synthesis <i>via</i> titanium-mediated multicomponent diimination of alkynes with C-nitrosos
作者:Connor W. Frye、Dominic T. Egger、Errikos Kounalis、Adam J. Pearce、Yukun Cheng、Ian A. Tonks
DOI:10.1039/d1sc06111a
日期:——
in situ via the multicomponent coupling of TiNR imidos with alkynes and nitriles. The formation of α-diimines is achieved through formal [4 + 2]-cycloaddition of the C-nitroso to the Ti and γ-carbon of the diazatitanacyclohexadiene followed by two subsequent cycloreversion steps to eliminate nitrile and afford the α-diimine and a Ti oxo.
α-二亚胺通常用作各种过渡金属催化过程的支持配体,尤其是在 α-烯烃聚合中。它们也是有价值的合成目标的前体,例如手性 1,2-二胺。它们的合成通常通过胺与α-二酮的酸催化缩合来进行。尽管这种方法很简单,但获取不对称的 α-二亚胺具有挑战性。在此,我们报道了 Ti 介导的炔烃的分子间二亚胺化,通过二氮杂环己二烯中间体与 C-亚硝基反应得到各种对称和不对称的 α-二亚胺。这些二氮杂钛环可以很容易地通过Ti 的多组分耦合原位获得NR 亚胺与炔烃和腈。α-二亚胺的形成是通过 C-亚硝基与二氮杂二氧化钛环己二烯的 Ti 和 γ-碳进行形式 [4 + 2]-环加成,然后进行两个后续的环还原步骤以消除腈并提供 α-二亚胺和 Ti氧代。
Switchable Synthetic Strategy toward Trisubstituted and Tetrasubstituted Exocyclic Alkenes
An efficient and facile method for the construction of tri- or tetrasubstituted exocyclic alkenes is achieved via a Cu(I)-catalytic system. This protocol exhibits mild conditions, low-cost catalyst, good functional group tolerance, and good yields. The selectivity toward tri- or tetrasubstituted alkenes can be delicately controlled by adjustment of base and solvent. A preliminary mechanism study manifested that the reaction undergoes a radical process, where B(2)pin(2) plays an indispensable role.
Preparation of functionally substituted allenes from methylacetylenes via propargylic lithium alanate or lithium borate intermediates