Isoprene-catalysed lithiation: deprotection and functionalisation of imidazole derivatives

Torregrosa, Rosario; Pastor, Isidro M.; Yus, Miguel

doi:10.1016/j.tet.2006.11.032

Cited by 17 publications

(4 citation statements)

References 39 publications

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“…Radical 4 can be further reduced by the excess lithium to give the anion 5 which can proceed once more as a base (Scheme 1). 9 Thus, isoprene-mediated lithiation of different imidazole derivatives, such as 1-methyl-, 10 1-phenyl-, 11 and 1-(diethoxymethyl)-1H-imidazole, 12 has been reported by us. In sharp contrast, the functionalization of other 1-alkylimidazoles, via the corresponding 2-lithio derivatives, has been less studied.…”

mentioning

confidence: 88%

“…MS (EI): m/z (%) = 125 (58) [M + ], 98 (93), 83 (100), 82 (96), 81 (12), 70 20, 69 (31), 56 (13), 55 (85), 54 (10).…”

Section: -Methylmentioning

confidence: 99%

“…13 C NMR (100 MHz, CDCl 3 ): δ = 13.4, 19.7, 32.2, 46.6, 76.2 (q, J = 29.8 Hz), 122.0, 124.2 (q, J = 286 Hz), 127.0, 127.2, 128.4, 129.1, 136.0, 143.7. MS (DIP, EI): m/z (%) = 299 (10) [M + + 1], 298 (27) [M + ], 297 (10), 269 (28), 256 (11), 251(14), 241(12), 230(15), 229 (90), 199 (60), 187(10), 173 (100), 165(17), 149 (13), 144(10), 133(10), 123(11), 117(10), 105 (51), 95 (39), 91(18), 77 (34), 69(10), 57(11), 55 (10), 43(15), 41(14).HRMS: m/z [M + ] calcd for C 15 H 17 F 3 N 2 O: 298.1293; found: 298.1289.…”

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confidence: 99%

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Isoprene as Lithiation Mediator: Synthesis of 2-Substituted 1-Alkylimidazole Derivatives

et al. 2012

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The lithiation of different imidazoles bearing a primary (i.e., butyl, pentyl, dodecyl) or secondary (i.e., cyclohexyl, 1-methylheptyl) alkyl substituent on the nitrogen has been successfully achieved by means of an isoprene-mediated protocol. The subsequent reaction of the 2-lithioimidazole intermediates with different electrophiles leads to the formation of interesting 1,2-disubstituted imidazoles.

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mentioning

confidence: 88%

“…MS (EI): m/z (%) = 125 (58) [M + ], 98 (93), 83 (100), 82 (96), 81 (12), 70 20, 69 (31), 56 (13), 55 (85), 54 (10).…”

Section: -Methylmentioning

confidence: 99%

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confidence: 99%

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Isoprene as Lithiation Mediator: Synthesis of 2-Substituted 1-Alkylimidazole Derivatives

et al. 2012

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“…The isoprene-catalysed lithiation of different 1-substituted imidazoles 132 (PG ¼ trityl, allyl, benzyl, vinyl, N,N-dimethylsulfamoyl, para-toluenesulfonyl, tert-butoxycarbonyl, acetyl, trimethylsilyl, tert-butyldimethylsilyl) leads to the cleavage of the protecting group producing 1H-imidazole (Scheme 10.59). However, the use of 1-(diethoxymethyl)imidazole (133) in the same lithiation reaction allows the preparation of the corresponding 2-lithio intermediate, which by reacting with different electrophiles such as, for example, benzaldehyde or N-phenyl-benzyl imine leads to 2-functionalized imidazoles (Scheme 10.60) [197]. As mentioned above, 5-lithiumimidazoles can be generated by direct deprotonation with an alkyllithium if the C2 position of the ring is blocked.…”

Section: Reactions Of N-metallated Imidazolesmentioning

confidence: 99%