Squaramide-catalysed asymmetric Friedel–Crafts alkylation of naphthol and unsaturated pyrazolones
作者:Ran Wei、Li Gao、Gaihui Li、Li Tang、Guoshun Zhang、Feilang Zheng、Heng Song、Qingshan Li、Shurong Ban
DOI:10.1039/d1ob00347j
日期:——
The first method for highly efficient asymmetric Michael-type Friedel–Craftsalkylation of naphthol and unsaturated pyrazolones has been accomplished under mild reaction conditions. In the presence of the chiral squaramide catalyst, a wide range of substrates are tolerated in excellent yields (up to 99%) with reasonable enantioselectivities (up to 96% ee).
在温和的反应条件下完成了萘酚和不饱和吡唑啉酮类高效不对称 Michael 型 Friedel-Crafts 烷基化的第一种方法。在手性方酸酰胺催化剂的存在下,可以以优异的收率(高达 99%)和合理的对映选择性(高达 96% ee)耐受各种底物。
Streocontrolled Construction of Six Vicinal Stereogenic Centers on Spiropyrazolones via Organocascade Michael/Michael/1,2-Addition Reactions
作者:Pankaj Chauhan、Suruchi Mahajan、Charles C. J. Loh、Gerhard Raabe、Dieter Enders
DOI:10.1021/ol501093v
日期:2014.6.6
A highlystereoselective one-pot procedure for the synthesis of spiropyrazolone derivatives bearing six contiguous stereogenic centers including two tetrasubstituted carbons has been developed. Under sequential catalysis by two organocatalysts, a cinchona-derived aminosquaramide and DBU, a series of diversely functionalized spiropyrazolones are obtained in good yields (47–62%) and excellent stereoselectivities
已经开发了一种用于合成具有六个连续立体中心(包括两个四取代碳)的螺吡唑酮衍生物的高度立体选择性一锅法。在两种有机催化剂(金鸡纳衍生的氨基方酰胺和 DBU)的连续催化下,以良好的收率(47-62%)和出色的立体选择性(高达 >25:1 dr 和 98-99% ee)获得了一系列不同功能化的螺吡唑酮. 螺吡唑酮的相反对映体也可通过使用假对映体氨基方酰胺催化剂获得。
Asymmetric Synthesis of Bispiro[γ-butyrolactone-pyrrolidin-4,4′-pyrazolone] Scaffolds Containing Two Quaternary Spirocenters via an Organocatalytic 1,3-Dipolar Cycloaddition
Enantiomerically enriched bispiro[γ‐butyrolactone‐pyrrolidin‐4,4′‐pyrazolone] skeletons were synthesized firstly through a simple organocatalytic 1,3‐dipolarcycloaddition reaction between α‐imino γ‐lactones and alkylidene pyrazolones, which afforded a diversity of bispirocyclic scaffolds in high yields and excellent diastereo‐ and enantioselectivities.
AbstractDrug‐like spirocyclic scaffolds have been prepared asymmetrically by fusing fully functionalized cyclohexanes with medicinally important pyrazolone, rhodanine, barbituric acid or indandione moieties. This approach utilizes an organocatalytic tandem Michael–Michael–aldol reaction that yields diverse chiral spirocyclic backbones containing six contiguous stereogenic centers and multiple functional groups. The target compounds are generated in good yield and with high stereoselectivity (up to 99 % ee and 95:5 dr). Intriguingly, diastereocontrol of the spiro‐products changes depending on the substrate.magnified image