Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides
The base-catalyzed isomerization of N-propargylamides or carbamates may furnish N-allenyl compounds (allenamides/allencarbamates) or further evolve to N-alkynyl compounds (ynamides or yncarbamates). The particular fate of this reaction varies from experiment to experiment and there is no clear rule...
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| Format: | Article |
| Language: | English |
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Beilstein-Institut
2015-08-01
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| Series: | Beilstein Journal of Organic Chemistry |
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| Online Access: | https://doi.org/10.3762/bjoc.11.156 |
| _version_ | 1818663400331280384 |
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| author | Armando Navarro-Vázquez |
| author_facet | Armando Navarro-Vázquez |
| author_sort | Armando Navarro-Vázquez |
| collection | DOAJ |
| description | The base-catalyzed isomerization of N-propargylamides or carbamates may furnish N-allenyl compounds (allenamides/allencarbamates) or further evolve to N-alkynyl compounds (ynamides or yncarbamates). The particular fate of this reaction varies from experiment to experiment and there is no clear rule for predicting the reaction outcome for a particular structure. With the support of ab initio and DFT computations, this work shows that observed results can be explained by assuming an exchange equilibrium between energetically close N-propargyl, allenyl and N-alkynyl forms and that the reaction outcome correlates to a particular equilibrium mixture. Due to the very small energy gap between the N-allenyl and N-alkynyl forms, small structural changes may easily alter the equilibrium position, explaining the variety of observed experimental results. Based on CBS-QB3 computations, the ωB97 functional provided reasonably accurate isomerization energies and could successfully predict the experimentally observed behavior for several examples from the literature. |
| first_indexed | 2024-12-17T05:16:15Z |
| format | Article |
| id | doaj.art-49a490540141403fbc2217d8341eaae5 |
| institution | Directory Open Access Journal |
| issn | 1860-5397 |
| language | English |
| last_indexed | 2024-12-17T05:16:15Z |
| publishDate | 2015-08-01 |
| publisher | Beilstein-Institut |
| record_format | Article |
| series | Beilstein Journal of Organic Chemistry |
| spelling | doaj.art-49a490540141403fbc2217d8341eaae52022-12-21T22:02:06ZengBeilstein-InstitutBeilstein Journal of Organic Chemistry1860-53972015-08-011111441144610.3762/bjoc.11.1561860-5397-11-156Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamidesArmando Navarro-Vázquez0Departamento de Química Fundamental, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, Cidade Universitária - Recife, PE - CEP 50.740-560, BrazilThe base-catalyzed isomerization of N-propargylamides or carbamates may furnish N-allenyl compounds (allenamides/allencarbamates) or further evolve to N-alkynyl compounds (ynamides or yncarbamates). The particular fate of this reaction varies from experiment to experiment and there is no clear rule for predicting the reaction outcome for a particular structure. With the support of ab initio and DFT computations, this work shows that observed results can be explained by assuming an exchange equilibrium between energetically close N-propargyl, allenyl and N-alkynyl forms and that the reaction outcome correlates to a particular equilibrium mixture. Due to the very small energy gap between the N-allenyl and N-alkynyl forms, small structural changes may easily alter the equilibrium position, explaining the variety of observed experimental results. Based on CBS-QB3 computations, the ωB97 functional provided reasonably accurate isomerization energies and could successfully predict the experimentally observed behavior for several examples from the literature.https://doi.org/10.3762/bjoc.11.156allenamideDFTisomerizationynamide |
| spellingShingle | Armando Navarro-Vázquez Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides Beilstein Journal of Organic Chemistry allenamide DFT isomerization ynamide |
| title | Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides |
| title_full | Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides |
| title_fullStr | Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides |
| title_full_unstemmed | Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides |
| title_short | Why base-catalyzed isomerization of N-propargyl amides yields mostly allenamides rather than ynamides |
| title_sort | why base catalyzed isomerization of n propargyl amides yields mostly allenamides rather than ynamides |
| topic | allenamide DFT isomerization ynamide |
| url | https://doi.org/10.3762/bjoc.11.156 |
| work_keys_str_mv | AT armandonavarrovazquez whybasecatalyzedisomerizationofnpropargylamidesyieldsmostlyallenamidesratherthanynamides |