Ir催化的不对称串联烯丙基化/ Iso -Pictet-Spengler环化反应对四氢-γ-咔啉的对映选择性
摘要:
用吲哚基烯丙基碳酸甲酯成功开发了Ir催化的不对称串联烯丙基化/ iso -Pictet-Spengler环化芳基烯丙二酸酯,为提供具有多个官能团和立体异构性的合成有用且具有生物活性的四氢-γ-咔啉衍生物提供了直接实用的方法。以高到高产量和出色的立体选择性控制居中(44%–96%产量,> 20:1 dr,94%→99%ee)。广泛的底物通用性,易于获得的底物和简单的手性催化系统显示了这种有效方案的巨大潜在实用性。
Catalytic chemoselective [3+3] cycloadditions of azomethine ylides with quinone monoimides leading to the construction of a dihydrobenzoxazine scaffold
A chiral thiourea catalyst possessing an amine function catalyzes an asymmetric [3+2] cycloaddition of azomethineylides to nitroolefins to provide highly functionalized pyrrolidines with high diastereo- and enantioselectivities (up to 98:1:1 dr, 92% ee). The reaction proceeds in a stepwise manner consisting of Michael addition and subsequent intramolecular aza-Henry reaction. Both reactions are promoted
Efficient Methods for the Synthesis of Benzopyrano[3,4-<i>c</i>]pyrrolidines by Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides with 3-Substituted Coumarins
Abstract With triethylamine as a catalyst, the 1,3-dipolarcycloaddition of azomethine ylides with 3-substituted coumarins proceeded smoothly under mild conditions to afford the desired products benzopyrano[3,4-c]pyrrolidines in good to excellent yields.
Efficient kinetic resolution of racemic 3-nitro-2H-chromenes by bifunctional thiourea afforded optically active (R)-3-nitro-2H-chromene derivatives with moderate to good enantioselectivities, which simultaneously gave the multifunctional 3,4-diphenyl-3a-nitrobenzopyrano-[3,4-c]-pyrrolidine-1,1-dicarboxylate derivatives with four vicinal chiral carbon centers.
Brønsted acid-promoted [3 + 3] cycloaddition of azomethine ylides with quinone monoimine provided an expedient access to dihydrobenzoxazine derivatives.