A study of the behaviour of some electron-rich 2-methyleneindolines (1-3) with different electron-poor reagents (formation of new carbon-carbon and nitrogen-carbon bonds) has furnished interesting results from both synthetic and the mechanistic viewpoints. Enamines 1-3 have been reacted with the beta-nitroenamines 4-7 (reaction CeCl3 center dot 7H(2)O promoted), giving the polymethine dyes 14-23. The same bases 1-3 have been nitroalkylated with the nitroolefins 8-10, furnishing the indolines 24-32, and the diastereoselectivity of the reaction has been thoroughly investigated. The most unexpected results derived from the first example of reaction of Fischer's bases with 1,2-diaza-1,3-butadienes. In fact, with 11-13, the 'unknown' indoline spirodihydropyrroles 33-40 were formed. Their structures were unambiguously assigned, and we determined, as an example, that of 33 by X-ray analysis. (c) 2006 Elsevier Ltd. All rights reserved.
Attanasi, O.A., Favi, G., Filippone, P., Forzato, C., Giorgi, G., Morganti, S., et al. (2006). On the reactivity of some 2-methyleneindolines with β-nitroenamines, α-nitroalkenes, and 1,2-diaza-1,3-butadienes. TETRAHEDRON, 62(26), 6420-6434 [10.1016/j.tet.2006.04.027].
On the reactivity of some 2-methyleneindolines with β-nitroenamines, α-nitroalkenes, and 1,2-diaza-1,3-butadienes
Giorgi, Gianluca;
2006-01-01
Abstract
A study of the behaviour of some electron-rich 2-methyleneindolines (1-3) with different electron-poor reagents (formation of new carbon-carbon and nitrogen-carbon bonds) has furnished interesting results from both synthetic and the mechanistic viewpoints. Enamines 1-3 have been reacted with the beta-nitroenamines 4-7 (reaction CeCl3 center dot 7H(2)O promoted), giving the polymethine dyes 14-23. The same bases 1-3 have been nitroalkylated with the nitroolefins 8-10, furnishing the indolines 24-32, and the diastereoselectivity of the reaction has been thoroughly investigated. The most unexpected results derived from the first example of reaction of Fischer's bases with 1,2-diaza-1,3-butadienes. In fact, with 11-13, the 'unknown' indoline spirodihydropyrroles 33-40 were formed. Their structures were unambiguously assigned, and we determined, as an example, that of 33 by X-ray analysis. (c) 2006 Elsevier Ltd. All rights reserved.
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https://hdl.handle.net/11365/9991
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