Asymmetric Synthesis of Functionalized Chromans via a One-Pot Organocatalytic Domino Michael-Hemiacetalization or -Lactonization and Dehydration Sequence
Starting from2-(nitrovinyl)phenols and various cyclic dicarbonyl nucleophiles, a one-pot thiourea-catalyzed diastereo- and enantioselective synthesis of polyfunctionalized chroman derivatives via a domino Michael-hemiacetalization and dehydration sequence as well as via a domino Michael-lactonization reaction is reported. Cyclopenta[b]chromenes, tricyclic spirochromans, and tetrahydro-1H-xanthenes
从2-(硝基乙烯基)苯酚和各种环状二羰基亲核试剂开始,通过多米诺米歇尔半缩醛化和脱水序列以及多米诺米歇尔-内酰胺化反应,通过一锅硫脲催化的非对映和对映选择性合成多官能化苯并二氢吡喃衍生物。报告。环戊二烯并[ b ]色烯,三环spirochromans,和四氢ħ -xanthenes轴承的各种官能团的可以以这种方式以良好至优异的产率(56-91%)合成并具有非常好的diastereo-(88-99% de)和对映选择性(83-99%ee)。 有机催化-多米诺反应-硫脲-一锅法-色原
Asymmetric Organocatalytic Cascade Michael/Hemiketalization/Retro-Aldol Reaction of 2-[(<i>E</i>)-2-Nitrovinyl]phenols with 2,4-Dioxo-4-arylbutanoates: A Convenient Access to Chiral α-Keto Esters
unprecedented organocatalyticenantioselective cascade Michael/hemiketalization/retro‐aldol reaction of 2‐[(E)‐2‐nitrovinyl]phenols and 2,4‐dioxo‐4‐arylbutanoates is described. With a bifunctional squaramide catalyst incorporating (1R,2R)‐1,2‐diphenylethane‐1,2‐diamine, the reactions afford products in 75–99% yields with 80–98% ee. This process provides an enantioselective pathway for the synthesis of chiral
Stereocontrolled construction of 3H-furo[3,4-b]chromen-1(9H)-one scaffolds via organocatalyzed Michael addition and the following intramolecular dehydration
An efficient approach for the stereocontrolledconstruction of 3H-furo[3,4-b]chromen-1(9H)-oneskeleton has been successfully developed through a sequential Michael addition/intramolecular dehydration strategy. The Michael addition of tetronic acid to 2-((E)-2-nitrovinyl)phenols catalyzed by a bifunctional squaramide derived from L-tert-leucine, and the subsequent intramolecular dehydration promoted
通过顺序迈克尔加成/分子内脱水策略,成功开发了一种立体控制3 H-呋喃并[3,4- b ] chromen-1(9 H)-骨架的有效方法。迈克尔加成特窗酸的2 - ((Ë)-2-硝基乙烯基)苯酚通过衍生自双官能squaramide催化大号-叔-亮氨酸,和由浓硫酸促进了随后的分子内脱水,顺利进行,得到相应的药学上有价值的3 H-呋喃并[3,4- b ] chromen-1(9 H)-one,可接受的收率为ee的79–97%。
Asymmetric Synthesis of cis-3,4-Disubstituted Chromans and Dihydrocoumarins via an Organocatalytic Michael Addition/ Hemiacetalization Reaction
of diphenyl prolinol trimethylsilylether, cis-3,4-disubstituted chromanols are obtained in high to excellent yields (81–98%) and stereoselectivities (dr: 86:14 to >99:1, ee 96 to >99%). The corresponding disubstituted chromans are available by dehydroxylation of the domino products in good to excellent yields (58–95%). Furthermore, oxidation of the domino products with pyridinium chlorochromate provided
Diastereodivergent Synthesis of Hexahydro‐6
<i>H</i>
‐benzo[
<i>c</i>
]chromen‐6‐one Derivatives Catalyzed by Modularly Designed Organocatalysts
作者:Satish Jakkampudi、Ramarao Parella、Hadi D. Arman、John C.‐G. Zhao
DOI:10.1002/chem.201806447
日期:2019.6.4
hexahydro‐6H‐benzo[c]chromen‐6‐one derivatives with good to high diastereoselectivities (up to 98:2 d.r.) and enantioselectivities (up to >99 % ee) has been achieved by using a domino Michael/Michael/hemiacetalization reaction between trans‐2‐hydroxy‐β‐nitrostyrenes and trans‐7‐oxo‐5‐heptenals followed by oxidation. With use of appropriate modularly designed organocatalysts (MDOs) that are self‐assembled
使用多米诺·迈克尔(Domino Michael)可实现非对映异构合成具有良好到高非对映选择性(高达98:2 dr)和对映选择性(高达> 99%ee)的六氢-6 H-苯并[ c ]铬n-6-one衍生物。反式-2-羟基-β-硝基苯乙烯与反式-7-氧代-5-庚烯之间的/ Michael /半缩醛化反应,然后氧化。通过使用适当的模块化设计的有机催化剂(MDO),这些有机催化剂是从氨基酸衍生物和金鸡纳生物碱衍生物就地自组装而成的,从中获得了所需的六氢-6 H-苯并[ c ]铬6-6-1的两种不同的非对映异构体。相同的基材。