Solvent controlled divergent syntheses of polysubstituted pyrroles and pyrrolo[2,3-b]-1,4-thiazines

Cheng, Ying; Kang, Zhi-Mei; Ma, Yang-Guang; Peng, Jiang-Hua; Liu, Meifang

doi:10.1016/j.tet.2008.05.044

Cited by 14 publications

(1 citation statement)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In 2006, we found for the first time that the zwitterions derived from N -heterocyclic carbenes and aryl isothiocyanates are unique ambident bis-dipolar compounds . Our experimental and theoretical studies indicated that these ambident 1,3-dipoles can act as either C + −C−S − or C + −C−N − dipolar species toward electron-deficient alkynes, alkenes, and ketenes to produce [3+2] cycloadducts, spiro-thiophenes 3 or spiro-pyrroles 4 as products or reaction intermediates (Scheme ) . The chem-selectivity between C−C−S and C−C−N cycloaddition is dependent upon both the electronic and steric effects of dipolarophiles.…”

Section: Introductionmentioning

confidence: 90%

An Experimental and Theoretical Study on the Interaction of N-Heterocyclic Carbene-Derived 1,3-Dipoles with Methoxycarbonylallenes: Highly Regio- and Stereoselective [3+2]-Cycloadditions Controlled by the Structures of N-Heterocycles of 1,3-Dipoles

Cheng

Wang

et al. 2009

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

The reactions of N-heterocyclic carbene-derived 1,3-dipoles with methoxycarbonylallenes were studied systematically by means of experimental and theoretical approach. The regioselectivity of [3+2]-cycloaddition of 1,3-dipoles toward the ester-substituted (activated) or alkyl-substituted (less activated) carbon-carbon double bond of methoxycarbonylallenes was strongly governed by the structures of N-heterocycles of 1,3-dipoles. In addition, the reaction temperature played an important part in regulating the regioselectivity of [3+2]-cycloaddition in some cases. While the reaction between benzimidazole carbene-derived 2-thiocarbamoyl benzimidazolium inner salts 5 and methoxycarbonylallenes 6 with or without heating gave predominantly adducts of C(+)-C-S(-) moiety to the alkyl-substituted double bond of methoxycarbonylallenes, triazole carbene-derived triazolium salts 14 underwent mainly its [3+2]-cycloaddition of C(+)-C-S(-) dipoles to the ester-substituted double bond of methoxycarbonylallenes. In the case of imidazoline carbene-derived 1,3-dipoles 10, the cycloaddition occurred between the C(+)-C-S(-) fragment and the activated double bond at room temperature, while in refluxing benzene, however, the same reaction yielded cycloadducts from the addition of 10 to the less activated double bond of methoxycarbonylallenes. DFT calculation revealed asynchronous cycloaddition mechanisms for the reactions of benzimidazole and imidazoline carbene-derived 1,3-dipoles with methoxycarbonylallenes, and a concerted mechanism for the reaction of triazole carbene-derived dipoles. The different regioselectivity of the reaction originated from the combination of electronic and steric effects of the reactants and the stability of the final products.

show abstract

Section: Introductionmentioning

confidence: 90%

An Experimental and Theoretical Study on the Interaction of N-Heterocyclic Carbene-Derived 1,3-Dipoles with Methoxycarbonylallenes: Highly Regio- and Stereoselective [3+2]-Cycloadditions Controlled by the Structures of N-Heterocycles of 1,3-Dipoles

Cheng

Wang

et al. 2009

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

ChemInform Abstract: Solvent Controlled Divergent Syntheses of Polysubstituted Pyrroles and Pyrrolo[2,3‐b]‐1,4‐thiazines.

Cheng

Kang

et al. 2008

ChemInform

View full text Add to dashboard Cite

Ring closure reactions O 0130Solvent Controlled Divergent Syntheses of Polysubstituted Pyrroles and Pyrrolo[2,3-b]-1,4-thiazines. -The reaction of arylthiocarbamoyl imidazolium inner salts (I) with ethyl propiolate can take two different pathways depending on the polarity of the solvent. Thus, vinylthiopyrrole derivatives (III)/(IV) are predominantly formed in more polar solvents like butanone or acetone. In less polar solvents like benzene or THF, the formation of pyrrolothiazines (V) is preferred. The reaction mechanism is discussed.

show abstract

Betaine Adducts of N‐Heterocyclic Carbenes: Synthesis, Properties, and Reactivity

2009

View full text Add to dashboard Cite

N‐Heterocyclic carbenes (NHCs) form stable zwitterionicadducts with a range of heteroallenes, ketenes, and allenes. Although the first representatives of this class of inner salts were first investigated as far back as the 1960s, they have enjoyed a sustained interest from the chemical community over the years. Depending on the nature of their anionic moiety, NHC betaines display a very broad palette of reactivities and have found applications in various fields of organic synthesis and catalysis. In this Microreview, the synthesis, properties, and reactivity of NHC betaines are surveyed. The NHCs under consideration include ylidenes derived from imidazole, benzimidazole, imidazoline, thiazole, or triazole, and the heteroallenes investigated so far are carbon dioxide, carbon disulfide, isocyanates, isothiocyanates, and their selenium analogues. A historical background is provided for each type of adduct under consideration, but emphasis is placed mainly on developments that have appeared in the literature within the past few years. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

show abstract

Solvent controlled divergent syntheses of polysubstituted pyrroles and pyrrolo[2,3-b]-1,4-thiazines

Cited by 14 publications

References 22 publications

An Experimental and Theoretical Study on the Interaction of N-Heterocyclic Carbene-Derived 1,3-Dipoles with Methoxycarbonylallenes: Highly Regio- and Stereoselective [3+2]-Cycloadditions Controlled by the Structures of N-Heterocycles of 1,3-Dipoles

An Experimental and Theoretical Study on the Interaction of N-Heterocyclic Carbene-Derived 1,3-Dipoles with Methoxycarbonylallenes: Highly Regio- and Stereoselective [3+2]-Cycloadditions Controlled by the Structures of N-Heterocycles of 1,3-Dipoles

ChemInform Abstract: Solvent Controlled Divergent Syntheses of Polysubstituted Pyrroles and Pyrrolo[2,3‐b]‐1,4‐thiazines.

Betaine Adducts of N‐Heterocyclic Carbenes: Synthesis, Properties, and Reactivity

Contact Info

Product

Resources

About