- Heterogeneously porous γ-MnO2-catalyzed direct oxidative amination of benzoxazole through C-H activation in the presence of O2
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Oxidative amination of azoles through catalytic C-H bond activation is a very important reaction due to the presence of 2-aminoazoles in several biologically active compounds. However, most of the reported methods are performed under homogeneous reaction conditions using excess reagents and additives. Herein, we report the heterogeneous, porous γ-MnO 2-catalyzed direct amination of benzoxazole with wide range of primary and secondary amines. The amination was carried under mild reaction conditions and using molecular oxygen as a green oxidant, without any additives. The catalyst can easily be separated by filtration and reused several times without a significant loss of its catalytic performance. Of note, the reaction tolerates a functional group such as alcohol, thus indicating the broad applicability of this reaction.
- Pal, Provas,Giri, Arnab Kanti,Singh, Harshvardhan,Ghosh, Subhash Chandra,Panda, Asit Baran
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supporting information
p. 2392 - 2396
(2014/10/15)
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- Visible-light-initiated photo-oxidative cyclization of phenolic amidines using CBr4-A metal free approach to 2-aminobenzoxazoles
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A mild and efficient one-pot operation for the amination of benzoxazoles has been achieved via ring opening of benzoxazoles followed by visible-light-mediated aerobic photo-oxidative cyclization of the resulting o-phenolic amidines using CBr4 as a mild oxidant. The protocol is economical and environmentally benign as it utilizes visible light and does not require any photosensitizers, additives, heating or inert conditions.
- Keshari, Twinkle,Srivastava, Vishnu P.,Yadav, Lal Dhar S.
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p. 5815 - 5818
(2014/01/23)
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- Synthesis of 2-aminobenzoxazoles via copper-catalyzed electrophilic amination of benzoxazoles with O-benzoyl hydroxylamines
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An efficient copper-catalyzed electrophilic amination of benzoxazoles with O-benzoyl hydroxylamines is described, employing CuCl catalyst, PPh3 ligand, and LiOtBu base. This simple air-stable copper catalysis enables the preparation of various 2-aminobenzoxazole derivatives at room temperature in good yields.
- Yotphan, Sirilata,Beukeaw, Danupat,Reutrakul, Vichai
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p. 6627 - 6633
(2013/07/26)
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- A convenient one-pot synthesis of N-substituted 2-aminoazole derivatives
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A practical protocol for the one-pot synthesis of N-substituted 2-aminoazole derivatives is described, employing simple azole substrates, nitrogen nucleophiles, lithium tert-butoxide as the base, and iodine to mediate carbon-nitrogen bond formation. This method proceeds at room temperature under an air atmosphere using a normal benchtop set-up, or can be performed conveniently using microwave irradiation. Georg Thieme Verlag Stuttgart - New York.
- Yotphan, Sirilata,Beukeaw, Danupat,Reutrakul, Vichai
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supporting information
p. 936 - 942
(2013/05/09)
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- Amination of benzoxazoles and 1,3,4-oxadiazoles using 2,2,6,6- tetramethylpiperidine-N-oxoammonium tetrafluoroborate as an organic oxidant
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No transition metals are necessary to convert benzoxazoles and 1,3,4-oxadiazoles into the corresponding pharmacologically interesting 2-aminated heterocycles by formal direct C(2)-amination using tetramethylpiperidine-N-oxoammonium tetrafluoroborate (TEMPO+BF 4-) as an oxidant (see scheme; TEMP=2,2,6,6- tetramethylpiperidine; TfOH=trifluoromethanesulfonic acid).
- Wertz, Sebastian,Kodama, Shintaro,Studer, Armido
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p. 11511 - 11515
(2012/01/11)
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- Serotonin 5-HT3 receptor partial activator
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This invention provides a serotonin 5-HT3 receptor partial activator which has a serotonin 5-HT3 receptor activating action, in addition to its serotonin 5-HT3 receptor antagonism, and does not cause constipation as a side effect. Particularly, based on the finding that newly synthesized benzoxazole derivatives typified by the compounds of the following formula (2) have strong serotonin 5-HT3 receptor antagonism and serotonin 5-HT3 receptor activating action, this invention provides these benzoxazole derivatives as serotonin 5-HT3 receptor partial activators. In the above formula, R1 to R4 may be the same or different from one another and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted lower alkenyl group or a substituted or unsubstituted amino group, or two groups of R1 and R2 may be linked together to form a ring structure, namely benzene ring; R5 represents a hydrogen atom, a substituted or unsubstituted lower alkyl group or a substituted or unsubstituted lower alkenyl group; and m is an integer of 1 to 4.
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- SYNTHESIS AND IR SPECTRA OF SOME 2-AMINOBENZOXAZOLE DERIVATIVES
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A large number of 5-nitro-, 6-nitro-, 5-chloro-, and 6-bromo-2-aminobenzoxazoles were synthesized by the reaction of benzoxazoline-2-thiones with various amines.It was shown by IR spectroscopy that all of the compounds exist in the amino form in solution,
- Simov, D.,Davidkov, K.
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p. 437 - 440
(2007/10/02)
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