Benzopyrans. Part 41. Reactions of 2-(2-dimethylaminovinyl)-1-benzopyran-4-ones with various dienophiles
作者:Chandra Kanta Ghosh、Samita Bhattacharyya、Chandreyi Ghosh、Amarendra Patra
DOI:10.1039/a903145f
日期:——
propiolate (EP) ultimately gives xanthenones 33, 34 and 37, respectively, the latter being admixed with flavone 43. Enamine 2, cyclisable to xanthenone 11, gives 33 and 35 with DMAD, and 37 and 44 with EP. Reaction of 3 with DMAD affords 36 exclusively.
Enantioselective Synthesis of Chromanones through Organocatalytic Tandem Reactions
作者:Mengxue Lu、Xin Wang、Zongli Xiong、Jingxiang Duan、Wen Ren、Weijun Yao、Yi Xia、Zhen Wang
DOI:10.1002/adsc.202001031
日期:2020.12.8
An enantioselective approach to lactone‐fused chromanone derivatives from 1‐(2‐hydroxyaryl)‐1,3‐diketones and α,β‐unsaturated aldehydes under mild conditions has been developed, which included organocatalytic stepwise Michaeladdition/ cycloketalization/hemiacetalization and followed by oxidation reaction. In the presence of chiral amine organocatalyst and an additional salicylic acid, a wide range
PPh3-catalyzed unexpected α-addition reaction of 1-(o-hydroxyaryl)-1,3-diketones to terminal alkynoates: a straightforward synthesis of multifunctional vinylesters
PPh3-catalyzed α-addition reactions of 1-(o-hydroxyaryl)-1,3-diketones to terminal alkynoates involving carbonâcarbon bond cleavage to give multifunctional vinylesters are described.
An organocatalytic enantioselective synthesis of δ‐lactone‐fused 4‐chromanones was demonstrated using 1‐(2‐hydroxyaryl)‐1,3‐butanedione and α,β‐unsaturated aldehydes in the presence of the Jørgensen‐Hayashi catalyst. The reaction proceeded through a Michael addition/cycloketalization/hemiacetalization sequence, and the resulting hemiacetals were oxidized into the corresponding lactone derivatives in