A practical method for the synthesis of pyrrolizidine, indolizidine and pyrroloazepinolizidine nucleus
作者:Tomás Quiroz、David Corona、Adrián Covarruvias、José Gustavo Avila-Zárraga、Moisés Romero-Ortega
DOI:10.1016/j.tetlet.2007.01.015
日期:2007.2
The alkylation of α,ω-dibromoalkanes, with the sodium salt of succinimide, followed by the reduction with sodium borohydride gives the respective N-ω-bromoalkyl-5-hydroxy-2-pyrrolidinones. These substrates are precursors of N-acyliminium ions under acidic conditions. The condensation of these intermediates with ethyl malonate in the presence of TiCl4 and diisopropylethylamine following the intramolecular
用琥珀
酰亚胺的
钠盐将α,ω-二
溴烷烃烷基化,然后用
硼氢化钠还原,得到各自的N -ω-
溴烷基-
5-羟基-2-吡咯烷酮。这些底物是在酸性条件下N-酰基
亚胺离子的前体。在分子内环化之后,在TiCl 4和
二异丙基乙胺的存在下,这些
中间体与
丙二酸乙酯的缩合提供了以高收率将取代的
吡咯烷
酮,
吲哚嗪
酮和
吡咯并ze庚啶
酮基
酮核形成的便利途径。