Enantioselective Route to β-Silyl-δ-keto Esters by Organocatalyzed Regioselective Michael Addition of Methyl Ketones to a (Silylmethylene)malonate and Their Use in Natural Product Synthesis
作者:Sunil Ghosh、Raghunath Chowdhury
DOI:10.1055/s-0030-1260036
日期:2011.6
potential. This has been demonstrated by the synthesis of a suitably substituted β-silyl-δ-keto ester as an advanced intermediate for a chiral hydroxylated pyrrolidine natural product, (+)-preussin. Silicon-controlled diastereoselective reduction of the ketone functionality of β-silyl-δ-keto esters followed by lactonization of the resulting hydroxy esters gave disubstituted δ-valerolactones. Advanced
(S)-N催化烷基甲基酮通过乙酰基甲基末端通过迈克尔直接加成到[[[二甲基(苯基)甲硅烷基]亚甲基}丙二酸二乙酯上。-(吡咯烷-2-基甲基)吡咯烷/三氟乙酸组合,具有高收率和优异的区域选择性和对映选择性。酮加合物可以很容易地进行脱乙氧基羰基化反应,得到具有极佳合成潜力的β-甲硅烷基-δ-酮酸酯。通过合成适当取代的β-甲硅烷基-δ-酮酸酯作为手性羟基化吡咯烷天然产物(+)-普鲁斯丁的高级中间体,可以证明这一点。硅控制的β-甲硅烷基-δ-酮酸酯的酮官能度的非对映选择性还原,然后将所得羟基酯内酯化,得到二取代的δ-戊内酯。已经获得了天然产物的对映体的高级中间体,即(+)-马来酰内酯和(+)-mevinolin类似物,以及天然产物的对映体,即(-)-四氢脂肪抑素和(+)-5-十六烷醇。 迈克尔加成-有机硅化合物-甲基酮-有机催化-区域选择性-天然产物