A novel [4+1] spiroannulation of o‐ & p‐bromophenols with α,β‐unsaturated imines has been developed for the direct synthesis of a new family of azaspirocyclic molecules. Notably, several other halophenols (X=Cl, I) were also applicable for this transformation. Moreover, a catalytic asymmetric version of the reaction was realized with 1‐bromo‐2‐naphthols by using a chiral ScIII/Py‐Box catalyst. Mechanistic
已经开发了一种新颖的[4 + 1]邻和对溴苯酚与α,β-不饱和亚胺螺环合成的方法,用于直接合成新的氮杂螺环分子家族。值得注意的是,其他几种卤代酚(X = Cl,I)也适用于该转化。此外,通过使用手性Sc III / Py-Box催化剂,使用1-溴-2-萘酚实现了反应的催化不对称形式。机理研究表明,该多米诺反应是通过苯酚衍生物在其卤代位置的亲电触发的脱芳香化作用进行的,然后通过基于自由基的S RN 1机理用N-亲核试剂进行卤素置换。
Enantioselective Friedel–Crafts reactions between phenols and N-tosylaldimines catalyzed by a leucine-derived bifunctional catalyst
作者:Guo-Xing Li、Jin Qu
DOI:10.1039/c2cc31735d
日期:——
Enantioselective FriedelâCrafts reactions between phenols and N-tosylaldimines were developed using a bifunctional catalyst readily prepared from L-leucine. The chiral benzylic amine products were obtained in high yields (up to 96% yield) and good to high enantiomeric excesses (up to 95% ee).
Chiral‐Directing‐Group‐Assisted Rhodium(III)‐Catalyzed Asymmetric Addition of Inert Arene C−H Bond to Aldimines with Subsequent Intramolecular Cyclization
作者:Xuhong Cai、Wenkun Chen、Ruifang Nie、Jun Wang
DOI:10.1002/chem.202103319
日期:2021.12
An asymmetric rhodium(III)-catalyzed C−H bond addition to aldimines followed by subsequent intramolecular cyclization to form chiral isoindolinones has been achieved by using a chiral directing group. Various substituted benzamides and aldimines have been smoothly transformed to the corresponding products in up to 68 % yield with up to 93 % ee.
A Chiral Disulfoxide Ligand for the Efficient Rhodium‐Catalyzed 1,2‐Addition of Arylboroxines to
<i>N</i>
‐Tosylarylimines
作者:Guang‐Zhen Zhao、Gellért Sipos、Alvaro Salvador、Arnold Ou、Pengchao Gao、Brian W. Skelton、Reto Dorta
DOI:10.1002/adsc.201500975
日期:2016.6.2
active pharmaceutical ingredients. Herein, we report a rhodium precatalyst with a chiral disulfoxide ligand that effects the 1,2‐addition of arylboroxines to aromatic imines to give high yields and high enantioselectivities of these products. The present paper describes a system that is very simple, where the ease of synthesis of the chiral ligand is combined with low catalyst loadings and reaction conditions
Enantioselective Synthesis of 3,5,6‐Substituted Dihydropyranones and Dihydropyridinones using Isothiourea‐Mediated Catalysis
作者:Daniel G. Stark、Louis C. Morrill、David B. Cordes、Alexandra M. Z. Slawin、Timothy J. C. O'Riordan、Andrew D. Smith
DOI:10.1002/asia.201500907
日期:2016.2
isothiourea-catalyzed processes has been expanded and explored through the use of 2-N-tosyliminoacrylates and 2-aroylacrylates in a Michael addition-lactonization/lactamization cascade reaction. Notably, to ensure reproducibility it is essential to use homoanhydrides as ammonium enolate precursors with 2-aroyl acrylates, while carboxylic acids can be used with 2-N-tosyliminoacrylates, delivering a range of 3,5,6-substituted