Carbonyl Allylation in the Absence of Preformed Allyl Metal Reagents: Reverse Prenylation via Iridium-Catalyzed Hydrogenative Coupling of Dimethylallene
摘要:
Iridium-catalyzed hydrogenation of dimethylallene in the presence of aromatic, heteroaromatic, and aliphatic carbonyl electrophiles 1a-12a delivers products of reverse prenylation 1b-12b. Reductive coupling of dimethyl allene to aldehyde 8a under an atmosphere of deuterium provides deuterio -8b. As revealed by H-2 NMR analysis, deuterium incorporation is observed at the vinylic position (80% H-2). Unlike established methods for carbonyl allylation, the present protocol circumvents the use of stoichiometrically preformed organometallic reagents.
Carbonyl Allylation in the Absence of Preformed Allyl Metal Reagents: Reverse Prenylation via Iridium-Catalyzed Hydrogenative Coupling of Dimethylallene
作者:Eduardas Skucas、John F. Bower、Michael J. Krische
DOI:10.1021/ja075971u
日期:2007.10.1
Iridium-catalyzed hydrogenation of dimethylallene in the presence of aromatic, heteroaromatic, and aliphatic carbonyl electrophiles 1a-12a delivers products of reverse prenylation 1b-12b. Reductive coupling of dimethyl allene to aldehyde 8a under an atmosphere of deuterium provides deuterio -8b. As revealed by H-2 NMR analysis, deuterium incorporation is observed at the vinylic position (80% H-2). Unlike established methods for carbonyl allylation, the present protocol circumvents the use of stoichiometrically preformed organometallic reagents.
A Chemoenzymatic Approach to the Stereocontrolled Synthesis of the C1-C11 fragment of (+)-Peloruside A
and diastereoselective synthesis of the C1-C11fragment of the marine natural product (+)-peloruside A has been developed. Through enzymatic desymmetrization of diethyl 3-hydroxyglutarate with lipase B from Candida antarctica a large-scale access to enantiomerically highly enriched starting material was achieved. Subsequent stereo-generating key steps utilized in the synthesis were a Sharpless asymmetric
已开发出一种高效和非对映选择性合成海洋天然产物 (+)-peloruside A 的 C1-C11 片段。通过用来自南极念珠菌的脂肪酶 B 对 3-羟基戊二酸二乙酯进行酶促去对称化,实现了对对映体高度富集的起始材料的大规模获取。合成中使用的后续立体生成关键步骤是 Sharpless 不对称二羟基化和双重非对映选择性 Mukaiyama 醛醇反应,以在 C2、C3、C5、C7 和 C8 处建立具有正确绝对构型的立体中心。