The p-Donor Ability of Vinamidine Chelates (Co, Ni, Cu, Zn, Pd) Assessed by X-Ray, IR and NMR
摘要:
Formyl groups were used as reporter substituents attached to positions with high pi-electron densities in the vinamidine moieties of a 2,3-dihydro-1,4-diazepinium cation (7a) and of five metal complexes (9a-e). X-Ray structure analyses of the latter indicated significant pi donation to the coplanar formyl groups but insignificant changes of the formyl geometry. Infrared wave numbers in solution revealed a weak pi donation from the vinamidinium system (79) and a uniformly strong one from the metal bis(chelates) (9a-e), but infrared intensities were inconclusive. However, clear evidence emerged from the rates of aldehyde rotation at the vinamidine moieties, as measured for these diamagnetic or paramagnetic heterocycles by H-1 nmr: The pi-donor chararacters were energetically quantified by comparisons of literature data with the rotational barriers 11.0 kcal/mol at vinamidinium(in 79) and 14.7-15.8 kcal/mol at vinamidin(id)e (in 9a, b, d and e).
尽管应用广泛,但迄今为止,选择性和多样化地获取N,N'-二芳基乙烷-1,2-二胺仍然是一个挑战。在这里,通过开发一种双功能钴单原子催化剂(Co SA -N/NC),我们提出了一种通过廉价且丰富的硝基芳烃和甲醛的选择性还原偶联直接合成此类化合物的通用方法,具有良好的底物和功能相容性,一种易于获得的贱金属催化剂,具有出色的可重复使用性以及高步骤效率和原子效率。机理研究表明,N锚定的钴单原子(CoN 4)作为还原过程的催化活性位点,N掺杂的碳载体富集了HCHO,及时捕获了原位形成的羟胺,并在弱电条件下提供了所需的硝酮。碱性条件下,随后硝酮和亚胺的逆电子需求1,3-偶极环加成反应,随后环加合物的加氢脱氧反应提供产物。在这项工作中,催化剂控制的硝基芳烃还原原位产生特定结构单元的概念预计将开发出更有用的化学转化。
β-Amino alcohols from anilines and ethylene glycol through heterogeneous Borrowing Hydrogen reaction
作者:Pedro J. Llabres-Campaner、Rafael Ballesteros-Garrido、Rafael Ballesteros、Belén Abarca
DOI:10.1016/j.tet.2017.08.006
日期:2017.9
Borrowing Hydrogen (BH), also called Hydrogen Autotransfer (HA), reaction with neat ethylene glycol represents a key step in the preparation of β-amino alcohols. However, due to the stability of ethylene glycol, mono-activation has rarely been achieved. Herein, a combination of Pd/C and ZnO is reported as heterogeneous catalyst for this BH/HA reaction. This system results in an extremely air and moisture
Organometallic ruthenium complexes and related methods for the preparation of tetra-substituted and other hindered olefins
申请人:Berlin Jacob
公开号:US20070282148A1
公开(公告)日:2007-12-06
The invention relates to ruthenium alkylidene complexes having an N-heterocyclic carbene ligand comprising a 5-membered heterocyclic ring having a carbenic carbon atom and at least one nitrogen atom contained within the 5-membered heterocyclic ring, wherein the nitrogen atom is directly attached to the carbenic carbon atom and is substituted by a phenyl ring, and wherein the phenyl ring has a hydrogen at either or both ortho positions and is substituted at at least one ortho or meta position. The invention also relates to an olefin metathesis reactions and particularly to the preparation of tetra-substituted cyclic olefins via a ring-closing metathesis.
ORGANOMETALLIC RUTHENIUM COMPLEXES AND RELATED METHODS FOR THE PREPARATION OF TETRA-SUBSTITUTED AND OTHER HINDERED OLEFINS
申请人:BERLIN Jacob
公开号:US20120123133A1
公开(公告)日:2012-05-17
The invention relates to ruthenium alkylidene complexes having an N-heterocyclic carbene ligand comprising a 5-membered heterocyclic ring having a carbenic carbon atom and at least one nitrogen atom contained within the 5-membered heterocyclic ring, wherein the nitrogen atom is directly attached to the carbenic carbon atom and is substituted by a phenyl ring, and wherein the phenyl ring has a hydrogen at either or both ortho positions and is substituted at at least one ortho or meta position. The invention also relates to an olefin metathesis reactions and particularly to the preparation of tetra-substituted cyclic olefins via a ring-closing metathesis.