Conversion of 2′-hydroxychalcones to flavanones catalyzed by cobalt Schiff base complex
TL;DR: In this paper, it was shown that base catalysis by Co(salpr) (OH) produced in situ is responsible for the reaction, which is found to proceed reversibly.
About: This article is published in Tetrahedron Letters.The article was published on 1989-01-01. It has received 26 citations till now. The article focuses on the topics: Schiff base.
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TL;DR: This review article summarizes the applications of bismuth(III) compounds in organic synthesis since 2002 and is largely organized by the reaction type although some reactions can be placed in multiple sections.
Abstract: This review article summarizes the applications of bismuth(III) compounds in organic synthesis since 2002. Although there are an increasing number of reports on applications of bismuth(III) salts in polymerization reactions, and their importance is acknowledged, they are not included in this review. This review is largely organized by the reaction type although some reactions can clearly be placed in multiple sections. While every effort has been made to include all relevant reports in this field, any omission is inadvertent and we apologize in advance for the same (358 references).
219 citations
TL;DR: In this paper, the authors investigated the possibility of using camphorsulfonic acid as chiral Bronsted acid catalysts for asymmetric cyclization of 2-hydroxychalcones to flavanones.
68 citations
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TL;DR: This chapter discusses the five remaining flavonoid structural types, here collectively known as the minor flavonoids, chalcones, aurones, dihydrochalcone, flavanones and diHydroflavonols, in the same order and format as used in the earlier two volumes.
Abstract: It is the purpose of this chapter to discuss the five remaining flavonoid structural types, here collectively known as the minor flavonoids, chalcones, aurones, dihydrochalcones, flavanones and dihydroflavonols. In order to orientate the reader it should be mentioned that chalcones, aurones and dihydrochalcones were discussed in Chapter 9 of The Flavonoids (1975) while flavanones and dihydroflavonols were treated in Chapter 11. In The Flavonoids-Advances in Research (1982) the five structural types were brought together in Chapter 6 under the present name. As far as is practicable I have presented the material here in the same order and format as used in the earlier two volumes. This makes it possible for the reader to compare current material easily and directly with material in the corresponding sections in the other two books. For the most part each structural type is presented in terms of increasing structural complexity: the primary classification is based upon B-ring oxygenation with the presentation of compounds in order of degree of A-ring oxygenation, O-alkylation and C-alkylation.
60 citations
01 Jan 1996
45 citations
TL;DR: A new family of benzene-based chiral heterodisulfoxide ligands L1-L5 was synthesized in a single step and applied in the rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to chromenones.
41 citations
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TL;DR: In this paper, the cobalt complex (bis(salicylidene-..gamma..-iminopropylmethylamine)cobalt(II), CoSMDPT, was shown to catalytically oxidize olefins in the presence of dioxygen or hydrogen peroxide.
Abstract: The cobalt complex (bis(salicylidene-..gamma..-iminopropyl)methylamine)cobalt(II), CoSMDPT, has been shown to catalytically oxidize olefins in the presence of dioxygen or hydrogen peroxide. When terminal olefins are oxidized, the methyl ketone and corresponding secondary alcohol are produced selectively. Internal as well as terminal olefins are oxidized. The most common pathway for the oxidation of olefins catalyzed by first-row transition metals-autoxidation-has been ruled out in this system. A Wacker-type mechanism, oxidation by peracids, and mechanisms involving the formation of peroxymetallocycles have also been ruled out. A new mechanism for O/sub 2/ oxidations is proposed which involves oxidation of the primary alcohol solvent by CoSMDPT to produce the corresponding aldehyde and hydrogen peroxide. Reaction of hydrogen peroxide with CoSMDPT occurs to form a cobalt hydroperoxide, which can be viewed as a stabilized hydroperoxy radical which has spin paired with the d/sub z/sup 2// electron of CoSMDPT. The cobalt hydroperoxide then adds to the olefin double bond, leading to formation of an alkyl hydroperoxide. Haber-Weiss decomposition of this alkyl hydroperoxide by CoSMDPT produces the observed ketone and alcohol products. Deactivation of the catalyst is due to oxidation of the ligand system of the cobalt complex as well as formation of a ..mu..-peroxo-dicobalt complex.
163 citations
TL;DR: In this article, the performance of Co(II)-Schiff base complexes toward selective oxygenation of organic molecules related to biological systems has been reviewed, and preliminary kinetic studies on the regioselective peroxyquinolato Co(III) complex formation show that the reaction involves a rate-determining hydrogen abstraction from the phenol substrate by a superoxo Co(3) complex initially formed, followed by rapid reduction of the resulting phenoxy radical with Co(2) species leading to the formation of a phenolato co-type complex, to which
98 citations
83 citations
TL;DR: In this article, a mechanism involving electron transfer from the substrate to cobalt(III) species is suggested, which leads to a high yield of secondary aromatic amines in high yield.
63 citations
TL;DR: Combined addition of yeast extract and cycloheximide suppressed the formation of retrochalcone, suggesting de novo synthesis, and a new metabolite was isolated from the induced cells.
46 citations