Mesoionic trifluoroacetylated 5-imino oxazolines: a re-examination of the structure using 13C NMR spectroscopy and cycloaddition reactions

Clerin, Daniel; Meyer, B.; Fleury, Jean‐Pierre; Fritz, Hans

doi:10.1016/s0040-4020(01)83235-x

Cited by 21 publications

(7 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These data indicate that the predominant tautomeric form of the salt in solution is the amino-form 5a [l l-121. The "C-nmr data is 5 also in agreement with the structure 5a for the salt [13]. Additional evidence for 5a being the predominant form is obtained by examination of the Reissert analog 4 formed on treatment of the salt 5 with aqueous sodium bicarbonate.…”

supporting

confidence: 72%

Synthesis and reactions of an open‐chain bis‐reissert salt analog

Iyer

Ratnam

Kulkarni

et al. 1986

Journal of Heterocyclic Chem

View full text Add to dashboard Cite

show abstract

supporting

confidence: 72%

Synthesis and reactions of an open‐chain bis‐reissert salt analog

Iyer

Ratnam

Kulkarni

et al. 1986

Journal of Heterocyclic Chem

View full text Add to dashboard Cite

show abstract

“…Method 2 : C- p -tolyl-N- p -chlorobenzoyl-N-methylglycine ( 6 a) [13] (0.5g, 1.57 mmol) and trifluoro-acetic anhydride (0.33g, 1.57 mmol) in chloroform (20 mL) were refluxed for one hour. After cooling to ambient temperature, carbon disulphide (10 mL) was added and the red reaction mixture refluxed for an additional hour.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Characterization of some New Mesoionic 1,3-Thiazolium-5-thiolates via Cyclodehydration and in situ 1,3-Dipolar Cycloaddition/Cycloreversion

et al. 2002

View full text Add to dashboard Cite

The title compounds were synthesized from C-aryl-N-methylglycines by N-aroylation followed by a cyclodehydration to form the corresponding 1,3-oxazolium-5-olates. These were not isolated but converted to the title compounds by an in situ 1,3-dipolar cycloaddition/cycloreversion sequence using carbon disulphide. We have studied the cyclodehydration step using acetic anhydride, trifluoroacetic anhydride and 1,3-dicyclohexyl-carbodiimide (DCC) at temperatures not exceding 60oC. Trifluroacetic anhydride proved to be the best reagent, giving a better yield and more easily purified products, although yields were also acceptable with the other two reagents.

show abstract

“…Replacement of the exocyclic oxygen atom in munchnones by a nitrogen atom (i.e., the transition to oxazolium-5-imidates 43) as before makes it possible to obtain compounds of the pyrrole series successfully from mesoionic oxazoles [15].…”

mentioning

confidence: 99%

Pyrroles from oxazoles

Бабаев

2012

Chem Heterocycl Comp

View full text Add to dashboard Cite

The review is devoted to the transformation of oxazoles (including those with cationoid and mesoionic structures) into compounds of the pyrrole series.The search for new methods for the synthesis of heterocyclic systems is always actual, and the development of new methods for the construction of the pyrrole ring is particularly significant: the pyrrole ring is the basis of life on Earth, as it is the major subunit of the vitally important biomolecules hemoglobin and chlorophyll. Like any other heterocycle, the pyrrole ring can either be assembled from acyclic precursors (one or several synthons) or another heterocycle can be used as its precursor, i.e., the pyrrole can be obtained by recyclization. Transformation of the oxazole ring can provide an interesting and unusual method for the production of pyrrole. Oxazoles are widely used as starting compounds in synthesis (e.g., of pyridines, imidazoles, and other heterocycles), but the diversity of the methods used for the transformation of oxazoles into pyrroles has not yet been duly reflected in the review literature.Preparation of this review was prompted by the discovery by author and his group of an entirely new family of oxazole transformations to pyrroles in a series of condensed heterocycles containing a bridging nitrogen atom. This transformation, which has already been included in the latest edition of the classic textbook [1] and in a recent monograph on the chemistry of oxazoles [2], deserves comparison with all other examples (both known and exotic) of the oxazole conversion to pyrroles. Such a comparison, with the emphasis on the structural type of the transformation and on comparison of monocycles with condensed systems, is the theme of the present review, which is of interest both to synthesis specialists and to a wide range of teachers and high school students.It is not necessary to duplicate the known examples of the pyrrole synthesis from oxazoles (presented in the books [2,3] in the form of detailed tables), and they will only be used in the general schemes in order to complete the picture. In view of classification it is convenient to divide the oxazoles from which pyrroles can be obtained into simple subfamilies -neutral oxazoles (mesoionic and "normal") and oxazolium salts. PYRROLES FROM "NORMAL" OXAZOLES WITH NEUTRAL STRUCTUREDuring Vilsmeier formylation of the oxazole 1 the pyrrole 2 was isolated [4].

show abstract

Mesoionic trifluoroacetylated 5-imino oxazolines: a re-examination of the structure using 13C NMR spectroscopy and cycloaddition reactions

Cited by 21 publications

References 17 publications

Synthesis and reactions of an open‐chain bis‐reissert salt analog

Synthesis and reactions of an open‐chain bis‐reissert salt analog

Synthesis and Characterization of some New Mesoionic 1,3-Thiazolium-5-thiolates via Cyclodehydration and in situ 1,3-Dipolar Cycloaddition/Cycloreversion

Pyrroles from oxazoles

Contact Info

Product

Resources

About