- RhIII-Catalyzed C?H Activation of Aryl Hydroxamates for the Synthesis of Isoindolinones
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RhIII-catalyzed C?H functionalization reaction yielding isoindolinones from aryl hydroxamates and ortho-substituted styrenes is reported. The reaction proceeds smoothly under mild conditions at room temperature, and tolerates a range of functional groups. Experimental and computational investigations support that the high regioselectivity observed for these substrates results from the presence of an ortho-substituent embedded in the styrene. The resulting isoindolinones are valuable building blocks for the synthesis of bioactive compounds. They provide easy access to the natural-product-like compounds, isoindolobenzazepines, in a one-pot two-step reaction. Selected isoindolinones inhibited Hedgehog (Hh)-dependent differentiation of multipotent murine mesenchymal progenitor stem cells into osteoblasts.
- Shaaban, Saad,Davies, Caitlin,Merten, Christian,Flegel, Jana,Otte, Felix,Strohmann, Carsten,Waldmann, Herbert
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supporting information
p. 10729 - 10734
(2020/07/25)
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- A Planar-Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones
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The rapid development of enantioselective C?H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar-chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert-butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)-proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee).
- Trifonova, Evgeniya A.,Ankudinov, Nikita M.,Mikhaylov, Andrey A.,Chusov, Denis A.,Nelyubina, Yulia V.,Perekalin, Dmitry S.
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p. 7714 - 7718
(2018/04/25)
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- Consecutive Lossen rearrangement/transamidation reaction of hydroxamic acids under catalyst- and additive-free conditions
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The Lossen rearrangement is a classic process for transforming activated hydroxamic acids into isocyanate under basic or thermal conditions. In the current report we disclosed a consecutive Lossen rearrangement/transamidation reaction in which unactivated hydroxamic acids were converted into N-substituted formamides in a one-pot manner under catalyst- and additive-free conditions. One feature of this novel transformation is that the formamide plays triple roles in the reaction by acting as a readily available solvent, a promoter for additive-free Lossen rearrangement, and a source of the formyl group in the final products. Acyl groups other than formyl could also be introduced into the product when changing the solvent to other low molecular weight aliphatic amide derivatives. The solvent-promoted Lossen rearrangement was better understood by DFT calculations, and the intermediacy of isocyanate and amine was supported well by experiments, in which the desired products were obtained in excellent yields under similar conditions. Not only monosubstituted formamides were synthesized from hydroxamic acids, but also N,N-disubstituted formamides were obtained when secondary amines were used as precursors.
- Jia, Mengmeng,Zhang, Heng,Lin, Yongjia,Chen, Dimei,Chen, Yanmei,Xia, Yuanzhi
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p. 3615 - 3624
(2018/05/26)
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- A new synthetic route to acylnitroso intermediates and their applications in HDA and ene reactions
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Background: Acylnitroso intermediates are considered as highly reactive and useful transient that have been used to synthesize a broad class of biological active compounds and synthetic drugs. Although there are some reported methods for the generation of these intermediates, but still challenge for mild and environmental benign protocol. Herein, we report the facile in situ synthesis of acylnitroso intermediates and their efficient hetero Diels-Alder (HDA) and ene reactions. Methods: Acylnitroso intermediates were readily obtained by hydrogen peroxide oxidation of hydroxamic acids catalyzed by Cu(I)-, Ir(I)- or Ru(II)-complexes and easily reacted with symmetric and asymmetric conjugated dienes beside their reaction with different alkenes which converted to biological active products. Results: The resulted acylnitroso intermediates were efficiently afforded the hetero Diels-Alder cycloadducts in the presence of cyclopentadiene, cyclohexadiene or α-terpinene in high yields along with good regioselectivity for the later. In case of N-dienyl lactams, the cycloadducts were formed in the yield up to 89% with complete regioselectivity. In the presence of optically active N-dienyl pyroglutamates, diastereoisomers were formed in high yields with up to 72 de. In addition, the transient acylnitroso species were trapped with alkene to form the ene product in yield up to 95 %. As an interesting transformation, the halocyclization of the ene products gave substituted oxazolidone in 77% yield which considered as one of the effective antimicrobial and antibiotic compounds. Conclusion: In a brief, we introduce a mild and effective route to deliver acylnitroso intermediates in situ by using environmentally benign, cost effective, and non-toxic hydrogen peroxide oxidant catalyzed by Cu(I)-, Ir(I)- or Ru(II)-complexes. Good to excellent yields, regio- and diastereoselectivity were obtained by trapping these intermediates in symmetric and asymmetric HDA and ene reactions. Interestingly, the ene products easily transformed to potent drugs.
- Fakhruddin, Ahmad,Abu-Elfotoh, Abdel-Moneim,Shibatomi, Kazutaka,Iwasa, Seiji
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supporting information
p. 196 - 205
(2018/03/09)
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- An efficient method for the preparation of hydroxamic acids
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Reactions of acyl chlorides with hydroxylamine hydrochloride and NaHCO 3 generate the corresponding hydroxamic acid products in ethyl acetate and water at room temperature for 5 min. This is a simple and efficient method to synthesize a wide range of hydroxamic acids from carboxylic acids in excellent yield and high purity after simple post-treatment without chromatographic purification. In this process, the highlights are the simple separation of products and cheaply available reagents.
- Gao, Xi-Ai,Wang, Xian-Xue,Yan, Hao,Li, Jian,Yan, Ru-Long,Huang, Guo-Sheng
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p. 381 - 385
(2013/05/22)
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- A convenient one-pot synthesis of aryl amines from aryl aldoximes mediated by Koser's reagent
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A simple and convenient procedure has been developed for the synthesis of aromatic amine by a one-pot reaction of aromatic aldoxime with hypervalent iodine(III) reagent [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser's reagent), in an alkaline medium. The aldoxime reacts with Koser's reagent to form an intermediate hydroxamic acid, which then undergoes Lossen type rearrangement to produce the desired amine. Several amines have been prepared which otherwise are difficult to prepare, by the reduction of corresponding nitro compounds. The scopes and limitations of this transformation have been discussed. ARKAT-USA, Inc.
- Ghosh, Harisadhan,Baneerjee, Arghya,Rout, Saroj Kumar,Patel, Bhisma K.
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experimental part
p. 209 - 216
(2011/05/30)
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- Hydroxamic acid and its derivatives as inhibitors of melanocyte tyrosinase for topical skin lighteners
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Methods, compounds, and formulations are provided to reduce pigmentation in mammalian skin, comprising hydroxamic acid and its derivatives, and especially benzohydroxamic acid and its derivatives. The compounds preferably inhibit pigment synthesis in melanocytes through inhibition of melanocyte tyrosinase. The methods can be used for lightening skin, and for treating uneven skin complexions, which result from hyperpigmentation-related medical conditions such as melasma, age spots, freckles, ochronosis, and lentigo. The compounds can be used medically or cosmetically, and preferably as topical formulations.
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- Protective solutions for organs
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Described is a protective solution for avoiding ischemic, storage or ischemia/reperfusion to organs, or to isolated cell systems, or to tissue components after perfusion, surgery, transplantation, or cryopreservation and subsequent reperfusion, which contains alkali ions, and if need be also alkaline earth ions as the electrolyte, a buffer e.g. on a histidine derivation basis, as well as a polyol and/or a saccharide, has an osmolarity of about 290 mosm/l to about 350 mosm/l, as well as a pH value of about 6.8 to about 7.4, and to which hydroxamic acid, and/or one or more hydroxamic acid derivatives are added.
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- Direct Conversion of Hydroxamic Acids into Nitriles
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Aromatic and aliphatic nitriles are prepared in excellent yield from the corresponding hydroxamic acids and phosphorus tribromide in benzene solution.
- Liguori, Angelo,Sindona, Giovanni,Romeo, Giovanni,Uccella, Nicola
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- REACTIONS BETWEEN HYDROXYLAMINES AND AROYL CYANIDES
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Aromatic hydroxylamines and sterically bulky aliphatic hydroxylamines react with aroyl cyanides to give exclusively the O-acyl derivatives.
- Prabhakar, S.,Lobo, A. M.,Marques, M. M.
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p. 1391 - 1394
(2007/10/02)
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