Rifamycin antibiotics—new compounds and synthetic methods. Part 3: Study of the reaction of 3-formylrifamycin SV with primary amines and ketones

Bujnowski, Krzysztof; Synoradzki, Ludwik; Zevaco, Thomas A.; Dinjus, E.

doi:10.1016/j.tet.2012.04.071

Cited by 5 publications

(8 citation statements)

References 17 publications

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“…In general, the spectra have to be recorded in DMSO due to the polarity of these rifamycin derivatives. Interestingly, compared to other imino derivatives we reported earlier, 19 the pyrrolidinium rifamycins derivatives display for the most part a clean, single set of signals, characteristic of stable derivatives undergoing no isomerization, also over a long period of time. Together with mass spectrometry and IR studies, the proposed structure of this compound could be determined.…”

Section: Nmr Studiesmentioning

confidence: 64%

“…This could be clearly followed on the TLC, ketone F having a characteristic Rf and red-orange spot on the elugram (the characterization of such ketones was described in detail in Ref. 19).…”

Section: Resultsmentioning

confidence: 95%

“…We reported earlier on new rifamycins displaying at C3 substituents with an a,b-unsaturated imine structure prone to isomerize at the enamine double bond to form syn and anti derivatives. 19 In the case of rifamycin 6, such an isomerization is not conceivable due to the symmetry of the pyrrolidinium moiety. We can only speculate, keeping in mind the free rotation around the C3eC1 0 and C2 0 -C3 0 4.…”

Section: Nmr Study Of Rifamycin 5: Characterization Of the Ansa-backbmentioning

confidence: 99%

“…This mechanism, partly inspired from the findings of our last investigation with 3-formylrifamycin SV, primary alkylamines and various ketones, 18,19 implies the use of acetic acid to fulfil the reaction. The in situ formed a-amino-alcohol A affords, after abstraction of a water molecule, the violet-blue pyrrolidinium compound B, observed via TLC.…”

Section: Nmr Study Of Rifamycin 5: Characterization Of the Ansa-backbmentioning

confidence: 99%

“…18 The third part of the study widened the scope and addressed the reaction with primary alkylamines and various ketones, which leads to new derivatives with 'C3-grafted' a,b-unsaturated imines. 19 In essence, the key stage in the synthesis of these compounds turned out to be an 'acid-catalysed' aldol-type condensation of two imines. The presence of an acid is definitely needed to 'activate' the aldehyde in rifamycin 1.…”

Section: Introductionmentioning

confidence: 99%

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Rifamycin antibiotics—new compounds and synthetic methods. Part 4: Study of the reaction of 3-formylrifamycin SV with secondary amines and ketones

et al. 2015

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a b s t r a c tIn the fourth part of an ongoing study dealing with the search for new rifamycin antibiotics, the reaction of 3-formylrifamycin SV (1) with secondary amines (a.o. pyrrolidine) and ketones of general structure R 1 eCH 2 eCOeR 2 (R 1 ¼H or alkyl and R 2 ¼alkyl or aryl) has been investigated. A new synthetic method for the preparation of stable zwitterionic rifamycin derivatives with a,b-unsaturated pyrrolidinium substituents at C3 of the naphthol chromophore has been developed. The structures of the isolated microcrystalline rifamycins and a general mechanism have been proposed on the basis of mass spectrometry results, FTIR, 1D and 2D NMR as well as TLC methods. Rifamycins displaying an aromatic substituent within the pyrrolidinium fragment at C3 displayed a good stability against hydrolysis and proved, in preliminary tests, to be active against TB and MOTT, the activity being for some particular strains (Myc. tbc. Bovis and Myc. scrofulaceum) higher than that observed with the reference drugs (RMP, RBT).

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Section: Nmr Studiesmentioning

confidence: 64%

Section: Resultsmentioning

confidence: 95%

Section: Nmr Study Of Rifamycin 5: Characterization Of the Ansa-backbmentioning

confidence: 99%

Section: Nmr Study Of Rifamycin 5: Characterization Of the Ansa-backbmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations