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Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts
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Titel: |
Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts |
In: | Beilstein Journal of Organic Chemistry, 15, 2019, S. 497-505 |
veröffentlicht: |
Beilstein Institut
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Umfang: | 497-505 |
ISSN: |
1860-5397 |
DOI: | 10.3762/bjoc.15.43 |
Zusammenfassung: | <jats:p>Adamantyloxyamine reacts with formaldehyde to give <jats:italic>N</jats:italic>-(adamantyloxy)formaldimine as a room-temperature-stable compound that exists in solution in monomeric form. This product was used for reactions with α-hydroxyiminoketones leading to a new class of 2-unsubstituted imidazole 3-oxides bearing the adamantyloxy substituent at N(1). Their reactions with 2,2,4,4-tetramethylcyclobutane-1,3-dithione or with acetic acid anhydride occurred analogously to those of 1-alkylimidazole 3-oxides to give imidazol-2-thiones and imidazol-2-ones, respectively. Treatment of 1-(adamantyloxy)imidazole 3-oxides with Raney-Ni afforded the corresponding imidazole derivatives without cleavage of the N(1)–O bond. Finally, the <jats:italic>O</jats:italic>-alkylation reactions of the new imidazole <jats:italic>N</jats:italic>-oxides with 1-bromopentane or 1-bromododecane open access to diversely substituted, non-symmetric 1,3-dialkoxyimidazolium salts. Adamantyloxyamine reacts with glyoxal and formaldehyde in the presence of hydrobromic acid yielding symmetric 1,3-di(adamantyloxy)-1<jats:italic>H</jats:italic>-imidazolium bromide in good yield. Deprotonation of the latter with triethylamine in the presence of elemental sulfur allows the in situ generation of the corresponding imidazol-2-ylidene, which traps elemental sulfur yielding a 1,3-dihydro-2<jats:italic>H</jats:italic>-imidazole-2-thione as the final product.</jats:p> |
Format: | E-Article |
Quelle: | Beilstein Institut (CrossRef) |
Sprache: | Englisch |