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Optically active imidazoles derived from enantiomerically pure trans-1,2-diaminocyclohexane


Mloston, G; Rygielska, D; Jasinski, M; Heimgartner, H (2011). Optically active imidazoles derived from enantiomerically pure trans-1,2-diaminocyclohexane. Tetrahedron: Asymmetry, 22(6):669-674.

Abstract

A new exploration of some monoprotected derivatives of trans-1,2-diaminocyclohexane as a platform for the synthesis of enantiomerically pure imidazole derivatives is described. The primary amino group (-NH2), present in the mono-imine derivative of salicylic aldehyde (hemi-salen derivative) 5 was used for sequential reactions with formaldehyde and a corresponding α-(hydroxyimino)ketone. (S)-(–)-1-Phenylethylamine was also used as starting material for the preparation of new imidazole N-oxides 7c and 10a-c, bearing a chiral N-(1-phenylethyl)carboxamido function at C(4). Imidazole N-oxides 10a-b possessing a Me or i-Pr group at N(1), respectively, follow the known sulfur-transfer pathway affording the corresponding imidazole-2-thiones 13a-b. However, in the case of imidazole N-oxide 10c with the bulky adamantan-1-yl substituent at N(1), the attempted ‘sulfur-transfer reaction’ led to the deoxygenated imidazole derivative 14. Finally, the same reaction with 7c, bearing the electron-withdrawing N-(1-phenylethyl)carboxamide residue at C(4) of the imidazole ring, yielded a mixture of deoxygenated imidazole 16 and imidazole-2-thione 15c.

Abstract

A new exploration of some monoprotected derivatives of trans-1,2-diaminocyclohexane as a platform for the synthesis of enantiomerically pure imidazole derivatives is described. The primary amino group (-NH2), present in the mono-imine derivative of salicylic aldehyde (hemi-salen derivative) 5 was used for sequential reactions with formaldehyde and a corresponding α-(hydroxyimino)ketone. (S)-(–)-1-Phenylethylamine was also used as starting material for the preparation of new imidazole N-oxides 7c and 10a-c, bearing a chiral N-(1-phenylethyl)carboxamido function at C(4). Imidazole N-oxides 10a-b possessing a Me or i-Pr group at N(1), respectively, follow the known sulfur-transfer pathway affording the corresponding imidazole-2-thiones 13a-b. However, in the case of imidazole N-oxide 10c with the bulky adamantan-1-yl substituent at N(1), the attempted ‘sulfur-transfer reaction’ led to the deoxygenated imidazole derivative 14. Finally, the same reaction with 7c, bearing the electron-withdrawing N-(1-phenylethyl)carboxamide residue at C(4) of the imidazole ring, yielded a mixture of deoxygenated imidazole 16 and imidazole-2-thione 15c.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2011
Deposited On:04 Aug 2011 07:41
Last Modified:07 Dec 2017 08:43
Publisher:Elsevier
ISSN:0957-4166
Publisher DOI:https://doi.org/10.1016/j.tetasy.2011.04.005

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