2009
DOI: 10.1021/jo802274q
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Facile Synthesis of β-Tribromomethyl and Dibromomethylenated Nitroalkanes via Conjugate Addition of Bromoform to Nitroalkenes

Abstract: Addition of bromoform to conjugated nitroalkenes in the presence of Mg provided beta-tribromomethyl nitroalkanes in good to excellent yields and diastereoselectivity. These novel Michael adducts, formed under radical conditions, underwent elimination of HBr in the same pot under reflux to afford beta-dibromomethylenated nitroalkanes in good yield. Alternatively, a one-pot high yielding synthesis of the dibromides was possible under anionic conditions via LDA mediated addition of bromoform to nitroalkenes.

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Cited by 22 publications
(45 citation statements)
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“…[14][15] Whereas the LDA-mediated reaction provided dibromomethylenated nitroalkenes 3 at low temperature (-78°C), the Mg-mediated reaction furnished nitrotribromides 2 at 0°C to room temperature, which underwent elimination under reflux conditions to form dibromides 3.…”
Section: Resultsmentioning
confidence: 99%
“…[14][15] Whereas the LDA-mediated reaction provided dibromomethylenated nitroalkenes 3 at low temperature (-78°C), the Mg-mediated reaction furnished nitrotribromides 2 at 0°C to room temperature, which underwent elimination under reflux conditions to form dibromides 3.…”
Section: Resultsmentioning
confidence: 99%
“…Da mesma forma que CHBr 3 (Esquema 1), 9 THMCs também são explorados na obtenção de di-haletos vinílicos que, 38,39 como importantes intermediários sintéticos, têm atraído a atenção, sobretudo, por serem estratégicos na síntese de compostos dotados de atividade anti-HIV. 38 A transformação de THMCs em di-haletos vinílicos mediada por índio metálico não é efetiva, uma vez que diclorometil cabinois alquila tratados com uma mistura de CuCl e bipiridina.…”
Section: Obtenção De Di-haletos Vinílicos E Z-cloro-vinil-olefinasunclassified
“…9,10 Dessa forma, o Esquema 1 apresenta a adição de bromofórmio a nitroalcenos, 7, na presença de magnésio, que, realizada a 0 o C, forma os adutos de Michael, β-tribromometilnitroalcanos, 8, com rendimentos de 56 a 95%. 9 Todavia, quando realizada sob refluxo ou com di-isopropilamideto de lítio (LDA), em vez de magnésio, a -78 o C, os produtos da reação são dibrometos vinílicos nitrados, 9, substratos bastante versáteis em síntese. Quando foram utilizados nitrocicloalcenos, os derivados cíclicos de 8 foram obtidos com diastereosseletividade de 75:25 a 100:0, sempre em favor do isômero trans.…”
Section: Introdução O Grupo Tricloro(bromo)metilaunclassified
“…14,15 Herein we report the addition of bromoform to an electron deficient carbon-heteroatom bond as in N-tosylimine and N-Boc-imine for the first time. 16 Results and discussion Treatment of N-tosylimines 5 with Mg-CHBr 3 under our previous optimized conditions, [12][13][14] viz. 8 equiv.…”
Section: Introductionmentioning
confidence: 99%
“…As part of our interest in the application of Mg-CHBr 3 as a reagent system for the facile introduction of the CBr 3 group, we have reported conjugate addition of bromoform to nitroalkenes 12 and enones. 13,14 In the case of α-substituted enones, especially cyclic ones, the Michael adducts spontaneously cyclized to afford dibromocyclopropanation products.…”
Section: Introductionmentioning
confidence: 99%