Catalyst-Free Conjugated Addition of Thiols to α,β-Unsaturated Carbonyl Compounds in Water
作者:Gopal L. Khatik、Raj Kumar、Asit K. Chakraborti
DOI:10.1021/ol060846t
日期:2006.5.1
[reaction: see text] Catalyst-free conjugateaddition of thiols to alpha,beta-unsaturated carbonylcompounds in water is reported. beta-Sulfido carbonylcompounds were formed at room temperature, in short times and with excellent chemoselectivity. Competitive dithiane/dithiolane formation, transesterification, and ester cleavage were not observed. Water played a dual role in simultaneously activating
Fluoroboric acid adsorbed on silica-gel (HBF4–SiO2) as a new, highly efficient and reusable heterogeneous catalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds
作者:Gaurav Sharma、Raj Kumar、Asit K. Chakraborti
DOI:10.1016/j.tetlet.2008.04.144
日期:2008.6
found to be a new and highly efficient heterogeneouscatalyst for thia-Michael addition to α,β-unsaturated carbonyl compounds under solvent-free conditions. In the case of 1,3-diaryl-2-propenones, the reactions are best carried out in MeOH. The rate of thia-Michael addition was dependent on the steric hindrance at the β-carbon of the α,β-unsaturated carbonyl substrate as well as surrounding the thiol
Scope and limitations of HClO4–SiO2 as an extremely efficient, inexpensive, and reusable catalyst for chemoselective carbon–sulfur bond formation
作者:Gopal L. Khatik、Gaurav Sharma、Raj Kumar、Asit K. Chakraborti
DOI:10.1016/j.tet.2006.11.050
日期:2007.1
cyclic and acyclic α,β-unsaturatedketones afforded excellent yields of the corresponding β-sulfidocarbonyls after 2 min to 2 h. In the case of dithiols, the bis-thia-Michael adducts were formed. The rate of the reaction was found to be dependent on the electronic and steric factors of the α,β-unsaturatedketones and the thiols. A substituent at the β-carbon of the α,β-unsaturatedketone offered steric
Triethylammonium acetate (TEAA): a recyclable inexpensive ionic liquid promotes the chemoselective aza- and thia-Michael reactions
作者:Akhilesh K. Verma、Pankaj Attri、Varun Chopra、Rakesh K. Tiwari、Ramesh Chandra
DOI:10.1007/s00706-008-0886-4
日期:2008.9
A new, highlyefficient, inexpensive, recyclable, mild, convenient, and green protocol for chemoselective aza/thia- Michaeladdition reactions of amines/thiols to α,β - unsaturated compounds using triethylammonium acetate ( TEAA ) ionic liquid was developed. The catalyst can be recycled ten times and obviate the need for toxic and expensive catalysts.
Highly Efficient Proline Ester-based Nickel Catalysts for Michael Addition of Thiophenols to α,β-Enones
作者:Way-Zen Lee、Chien-Wei Chiang、Girish M. Kulkarni、Ting-Shen Kuo
DOI:10.1002/jccs.201200386
日期:2013.3
Two N3O2 pentadentate ligands, BMPP and BPPP, were prepared for synthesizing highlyefficient nickel catalysts, [Ni(BMPP)(CH3CN)](ClO4)2 (1) and [Ni(BPPP)(CH3CN)](BPh4)(ClO4) (2), for thia‐Michaeladdition of thiophenols to α,β‐enones. X‐ray structures of 1 and 2 revealed that a labile CH3CN molecule was bound to the nickel center of the catalysts. ESI‐MS spectroscopy indicated that thiolate replaced