描述了几种 3,3-二取代的 2-芳基丙烯酸的合成。芳基乙醛酸酯和异亚丙基三苯基正膦之间的 Wittig 反应提供了一条有效的途径来制备 2-芳基-3-甲基巴豆酸酯。这些酯用 N-溴代琥珀酰亚胺溴化得到 3-溴甲基-2-芳基巴豆酸酯和-2-芳基异巴豆酸酯的混合物。3-溴甲基巴豆酸酯在加热时环化成内酯。还制备了2-芳基-3-叠氮甲基异巴豆酸和3-氨基甲基-2-苯基异巴豆酸。已从α-甲基-和α-乙基肉桂酸酯开始,开发了一种立体定向路线,用于制备 3-叠氮甲基-2-苯基异巴豆酸和顺式-3-叠氮甲基-2-苯基-2-戊烯酸。La synth8se de plusieurs acides aryl-2 acryliques dissubstituks en position-3,3 est dkcrite。La 反应 de Wittig effectuk entre desesters arylglyoxyliques
established, asymmetric hydrogenation of challenging tetrasubstituted α,β‐unsaturatedcarboxylicacids is rarely reported. We demonstrate enantioselective hydrogenation of cyclic and acyclic tetrasubstituted α,β‐unsaturatedcarboxylicacids via cobalt(II) catalysis. This protocol showed broad substrate scope and gave chiral carboxylicacids in good yields with excellent enantiocontrol (up to 98 % yield and
Superacid-promoted synthesis of indolizidine derivatives
作者:Sean Kennedy、Anila Kethe、Ahmad Qarah、Douglas A. Klumpp
DOI:10.1016/j.tetlet.2018.03.094
日期:2018.5
A series of amido-acetals were reacted with the Brønsted superacid, CF3SO3H, to provides indolizidine derives by a cyclization cascade. A mechanism is proposed involving formation of a vinylogous enol which undergoes a 6π-electrocyclization reaction with an adjacent N-acyl iminium ion group. With aryl substituents, there is a strong tendency for the N-acyl iminium ion group to undergo Friedel-Crafts
一系列酰胺基乙缩醛与布朗斯台德超酸CF 3 SO 3 H反应,通过环化级联反应提供吲哚并咪唑衍生物。提出了一种机理,该机理涉及形成乙烯基的烯醇,该乙烯基的烯醇与相邻的N-酰基亚胺离子基团进行6π-电环化反应。在具有芳基取代基的情况下,N-酰基亚氨基鎓离子基团具有与芳基基团一起进行Friedel-Crafts型环化的强烈趋势。合成方法用于制备生物碱天然产物ipalbidine。
Process-Scale Total Synthesis of Nature-Identical (−)-(S,S)-7-Hydroxycalamenal in High Enantiomeric Purity through Catalytic Enantioselective Hydrogenation
A process-scale stereoselective synthesis of nature-identical (−)-(S,S)-7-hydroxycalamenal (=(−)-(5S,8S)-5,6,7,8-tetrahydro-3-hydroxy-5-methyl-8-(1-methylethyl)naphthalene-2-carbaldehyde; (−)-1a) in 96% enantiomeric excess (ee) with the aid of chiral Ru complexes has been developed. The key step was the enantioselective hydrogenation of easily accessible 2-(4-methoxyphenyl)-3-methylbut-2-enoic acid