1613-83-8Relevant academic research and scientific papers
Unexpected Z/E isomerism of N-methyl-O-phosphothioyl benzohydroxamic acids, their oxyphilic reactivity and inertness to amines
Majewski, Arkadiusz,Chojnacki, Jaros?aw,Przychodzeń, Witold
, p. 1077 - 1091 (2021/01/11)
Thiophosphinoylation of N-methyl p-substituted benzohydroxamic acids using disulfanes (method A) or diphenylphosphinothioyl chloride (method B) provides only one conformer of the respective O-phosphothioyl derivative (X-ray and NMR analysis). Undergoing t
Late-Stage Photoredox C-H Amidation of N-Unprotected Indole Derivatives: Access to N-(Indol-2-yl)amides
Weng, Yue,Ding, Bo,Liu, Yunqing,Song, Chunlan,Chan, Lo-Ying,Chiang, Chien-Wei
supporting information, p. 2710 - 2714 (2021/05/05)
The late-stage functionalization of N-unprotected indoles can be useful for modifying low-molecular-weight drugs and bioactive peptides. Whereas indole carboxamides are valuable in pharmaceutical applications, the preparation N-(indol-2-yl)amides with similar structures continues to be challenging. Herein we report on visible-light-induced late-stage photoredox C-H amidation with N-unprotected indoles and tryptophan-containing peptides, leading to the formation of N-(indol-2-yl)amide derivatives. N-Unprotected indoles and aryloxyamides that contain an electron-withdrawing group could be coupled directly to eosin Y as the photocatalyst by irradiation with a green light-emitting diode at room temperature. Mechanistic studies and density functional theory calculations indicate that the transformation might proceed through the oxidative C-H functionalization of indole with a PS? to PS?- cycle. This protocol provides a new toolkit for the late-stage modification labeling and peptide-drug conjugation of N-unprotected indole derivatives.
Oxidative cleavage of hydroxamic acid promoted by sodium periodate
Yuan, Changchun,Du, Biao,Xun, Miao-Miao,Liu, Bo
, p. 3622 - 3628 (2017/06/13)
A series of hydroxamic acids, involving aliphatic, aromatic and cyclic substrates, were transformed to the corresponding carboxylic acids through NaIO4-mediated oxidative cleavage in mild conditions. Esterification of these acids with TMSCHN2 could result in formation of the corresponding methyl ester. This methodology makes good compensation for the existing methods transforming amides to esters. Our results also pave the way to harness hydroxamic acids as useful synthetic building blocks.
Determination of pKa's of hydroxamic acids by nucleophilic substitution reaction
Shrivastava, Ashish,Ghosh, Kallol K.,Dubey
, p. 1630 - 1634 (2008/09/19)
Acid dissociation constant (pKa) of some para-substituted benzohydroxamic, 4-XC6H4CONHOH, and N-methyl para-substituted benzohydroxamic acids, 4- XC6H4CON(OH) CH3, where X = H, CH3, CH3O, NO2, Cl, have been determined spectrophotometrically by nucleophilic substitution reactions of p-nitrophenyl acetate with hydroxamate ions at 27± 0.1°C. All reactions in this study follow pseudo-first order kinetics under condition of excess nucleophile. Good correlation has been observed between pKa and substitutent constants pointing out the validity of the Hammett equation. The kinetics results have been discussed on the basis of pKa and α-effect of hydroxamic acids.
Reactivity patterns of N-methylbenzhydroxamates. I. Studies of methyl transfer between N-methylbenzhydroxamates and arenesulfonates
Fountain, Kenneth R.,Fountain, Daniel P.,Michaels, Bernice,Myers, D. Brenton,Salmon, Jon K.,et al.
, p. 798 - 810 (2007/10/02)
The rates of methyl transfer between benzohydroxamates and sulfonates show large βnuc values (ca. 0.8) indicating much charge transfer to the C atom, similar to the results of N,N-dialkylaminofluorene anions.A small α effect shows that even in
The Reaction of N-Alkylhydroxamic Acids with Sulphinyl Chlorides
Banks, Malcolm R.,Hudson, Robert F.
, p. 1211 - 1216 (2007/10/02)
The reaction of several N-methylhydroxamic acids with methane- and benzene-sulphinyl chloride is shown to give an isolatable O-sulphinylated intermediate (IV) below 0 deg C.The intermediates decompose at ambient temperatures with simultaneous N-O and S-O bond fission to give the isomeric N-acyl-N-methylsulphonamide (V) and N-methyl-O-sulphonylhydroxamic acid (VI) by in-cage and free pair radical recombination. 1H and 13C n.m.r. spectra show strong polarisations in both sulphonamide (V) and O-sulphonylhydroxamic acid (VI), indicating radical cage mechanisms.In addition, a strong e.s.r. signal was observed due to the N-acyl- N-methylnitroxyl radical (X).
