Zinc Tetrafluoroborate Hydrate as a Mild Catalyst for Epoxide Ring Opening with Amines: Scope and Limitations of Metal Tetrafluoroborates and Applications in the Synthesis of Antihypertensive Drugs (<i>RS</i>)/(<i>R</i>)/(<i>S</i>)-Metoprolols
作者:Brahmam Pujala、Shivani Rana、Asit K. Chakraborti
DOI:10.1021/jo201473f
日期:2011.11.4
reaction at the benzylic carbon of the epoxide ring. A reversal of regioselectivity (91:1–69:31) in favor of the reaction at the terminal carbon of the epoxide ring was observed for reaction with morpholine. The regioselectivity was dependent on the electronic and steric factors of the epoxide and the pKa of the amine and independent of amine nucleophilicity. The role of the metal tetrafluoroborates is
已经研究了金属四氟硼酸盐与胺进行环氧化物开环反应的范围和局限性,并且发现Zn(BF 4)2 · x H 2 O是一种温和而有效的催化剂,在无溶剂条件下于200 ℃提供高收率。 rt具有出色的化学,区域和立体选择性。催化效率依次为Zn(BF 4)2 · x H 2 O≫ Cu(BF 4)2 · x H 2 O> Co(BF 4)2 ·6H 2 O≫ Fe(BF 4)2 ·6H2 O> LiBF 4与环己烯氧化物和Zn(BF 4)2 · x H 2 O≫ Co(BF 4)2 ·6H 2 O≫ Fe(BF 4)2 ·6H 2 O> Cu(BF 4)反应2 · x H 2 O,用于氧化二苯乙烯,但AgBF 4是无效的。对于苯乙烯氧化物与苯胺的反应,四氟硼酸金属具有相当的区域选择性(1:99–7:93),并且在环的苄基碳上具有优先反应。与吗啉反应时,观察到区域选择性的逆转(91:1–69:31),有
Magnetic Nano Fe3O4 Catalyzed Solvent-Free Stereo- and Regioselective Aminolysis of Epoxides by Amines; a Green Method for the Synthesis of β-Amino Alcohols
作者:Srinivasarao Babu、Amit Kumar、Ramarao Parella
DOI:10.1055/s-0033-1340844
日期:——
We report the use of magnetic nano Fe3O4 as a mild heterogeneous catalyst for the aminolysis of epoxides with amines. The approach constitutes a green method for the formation of a variety of β-amino alcohols with very high stereo- and regioselectivity under solvent-free and ambient reaction conditions. The aminolysis of chiral epoxides with amines gave the corresponding chiral β-amino alcohols with
Use of α-Allyloxy-α-trimethylsiloxyacetate for Reductive Imino Aldol Reaction Promoted by Titanium Tetraiodide: A Rapid Access to β-Amino-α-hydroxy Esters
作者:Makoto Shimizu、Tetsuya Sahara
DOI:10.1246/cl.2002.888
日期:2002.9
Under the influence of titaniumtetraiodide the reductive imino aldol reaction of α-allyloxy-α-trimethylsiloxyacetate proceeded with imines to give β-amino-α-hydroxy esters in good yields.
Synthesis of 1,3-oxazolidines by copper-catalyzed addition of acetone and ethyl diazoacetate to imines
作者:Seung-Han Lee、Jin Yang、Tae-Dong Han
DOI:10.1016/s0040-4039(01)00479-8
日期:2001.5
1,3-Oxazolidines are obtained in high yields by copper-catalyzed addition of ethyldiazoacetate to imines in the presence of acetone. Hydrolysis of the oxazolidines with 6N HCl yields 1,2-amino alcohols.
Zinc(II) Perchlorate Hexahydrate Catalyzed Opening of Epoxide Ring by Amines: Applications to Synthesis of (<i>RS</i>)/(<i>R</i>)-Propranolols and (<i>RS</i>)/(<i>R</i>)/(<i>S</i>)-Naftopidils
作者:Shivani、Brahmam Pujala、Asit K. Chakraborti
DOI:10.1021/jo062674j
日期:2007.5.1
perchlorate hexahydrate was found to be the best catalyst compared to other metal perchlorates. The counteranion modulated the catalytic property of the various Zn(II) compounds that followed the order Zn(ClO4)2·6H2O ≫ Zn(BF4)2 ∼ Zn(OTf)2 ≫ ZnI2 > ZnBr2 > ZnCl2 > Zn(OAc)2 > Zn(CO3)2 in parallelism with the acidic strength of the corresponding protic acids (except for TfOH). The applicability of the methodology