首次开发了膦催化的 2-(4 H-苯并[ d ][1,3]恶嗪-4-基)丙烯酸酯与异氰酸酯的对映选择性形式 (4 + 2)-环加成反应。手性膦有机催化剂对 2-(4 H-苯并[ d ][1,3]oxazin-4-yl) 丙烯酸酯的初始 S N 2' 攻击产生了关键的含膦偶极中间体,随后与异氰酸酯以 60-84% 的收率和 61-92% 的 ee 提供范围广泛的 3,4-二氢喹唑啉-2-酮。
Experimental and computational studies on H<sub>2</sub>O-promoted, Rh-catalyzed transient-ligand-free <i>ortho</i>-C(sp<sup>2</sup>)–H amidation of benzaldehydes with dioxazolones
We develop an efficient and convenient ligand-free, rhodium-catalyzed ortho-C(sp2)–H amidation of benzaldehydes with dioxazolones using H2O as the key promoter.
Rh-catalyzed Transient Directing Group Promoted C-H Amidation of Benzaldehydes Utilizing Dioxazolones
作者:Xiaoyang Wang、Song Song、Ning Jiao
DOI:10.1002/cjoc.201700726
日期:2018.3
Transition‐metal catalyzedC—H functionalization of benzaldehydes is of great interest in organic synthesis. Herein, we developed a transient directing group assisted amidation of benzaldehydes catalyzed by rhodium catalyst. With the employment of 10 mol% of 4‐trifluoromethyl aniline, the in situ generated imine groups as the directing group efficiently enable this transformation. By using this protocol
TBHP/CoCl<sub>2</sub>-Mediated Intramolecular Oxidative Cyclization of<i>N</i>-(2-Formylphenyl)amides: An Approach to the Construction of 4<i>H</i>-3,1-Benzoxazin-4-ones
作者:Junchao Yu、Daisy Zhang-Negrerie、Yunfei Du
DOI:10.1002/ejoc.201501359
日期:2016.1
The intramolecular oxidativecyclization of N-(2-formylphenyl)amides has been realized through an oxidative C(sp2)–O(sp2) bond-forming reaction between an aldehyde carbon and amide oxygen. This new strategy, which uses tert-butyl hydroperoxide (TBHP) as an oxidant and CoCl2 as the catalyst, allows for the efficient Co-catalyzed synthesis of useful benzoxazin-4-one derivatives and features readily available
KOtBu-mediated stereoselective addition of quinazolines to alkynes under mild conditions
作者:Dan Zhao、Qi Shen、Yu-Ren Zhou、Jian-Xin Li
DOI:10.1039/c3ob41083h
日期:——
A facile alkenylation of quinazolines with unactivated terminal alkynes has been achieved in the presence of KOtBu without the aid of any transition metal catalysts. The reaction is carried out under very mild conditions and shows a high stereoselectivity. A possible radical-based mechanism is also explored.
Rh<sup>III</sup>-Catalyzed site-selective amidation with nitrone as a traceless directing group: an approach to functionalized arylaldehydes
作者:Hong Deng、Hongji Li、Wenge Zhang、Lei Wang
DOI:10.1039/c7cc05297a
日期:——
An efficient Rh-catalyzed site-selective amidation of nitrones with 1,4,2-dioxazol-5-ones has been developed. The reaction can tolerate a number of groups and generates functionalized aldehydes in good yields. The significance of the amidation is highlighted by the late-stage transformation of the formed aldehydes.