AbstractA facile method for the stereoselective synthesis of trans‐2,3‐dihydrobenzofurans from ortho‐quinone methides in situ generated from readily available 2‐alkyl‐substituted phenols using silver oxide‐mediated oxidation has been developed. Additionally, the 2,3‐dihydrobenzofurans can be further transformed into the aromatized 2,3‐disubstituted benzofurans in the presence of DDQ.magnified image
A streamlined method for the enantioselective synthesis of 2-amino-4H-chromenes from readily available 2-alkyl-substitutedphenols and active methylene compounds bearing a cyano group with up to 97% ee is presented. This reaction is a cascade procedure including manganese dioxide mediated C–H oxidation for the generation of o-quinone methides and bifunctional squaramide-catalyzed Michael addition/cyclization
asymmetric synthesis of 4H-chromenes starting from 2-alkyl-substituted phenols. The aerobic oxidation toward a transient ortho-quinone methide was efficiently catalyzed by a manganese(III) species MnL3 while the ensuing Michael addition of β-dicarbonyl compounds proved to be catalyzed by a chiral manganese phosphate MnL2X*.
的组合原位形成MNL 3复合物(HL = Hacac或R(C = O)CH 2 CO 2 R)和手性磷酸HX *允许4的完全催化,不对称合成ħ -chromenes从2开始-烷基取代的酚。锰(III)物种MnL 3可以有效地催化向瞬态邻甲基苯甲酸的好氧氧化,而随后的β-二羰基化合物的迈克尔加成反应则被手性磷酸锰MnL 2 X *催化。
Enantioselective one-pot synthesis of 2-amino-4<i>H</i>-chromenes via C−H oxidation and Michael addition/ring closure sequences
作者:Kyeong Seop Kim、Dae Young Kim
DOI:10.1080/00397911.2021.2024572
日期:2022.1.17
Abstract The chiral 2-amino-4H-chromene derivatives were obtained from 2-alkyl-substituted phenol derivatives in moderate to high yields with excellent enantioselectivities through one-potcascade via C–H oxidation/Michael addition/ring closure sequences using a binaphthyl-modified organocatalyst with low catalyst loading (1.25 mol%).
One-Pot Synthesis of 3,4-Dihydrocoumarins via C-H Oxidation/Conjugate Addition/Cyclization Cascade Reaction
作者:Dae Young Kim
DOI:10.3390/molecules28196853
日期:——
The 3,4-dihydrocoumarin derivatives were obtained from 2-alkyl phenols and oxazolones via C–H oxidation and cyclization cascade in the presence of silver oxide (Ag2O) and p-toluenesulfonic acid as a Brønsted acid catalyst. This approach provides a one-pot strategy to synthesize the multisubstituted 3,4-dihydrocoumarins with moderate to high yields (64–81%) and excellent diastereoselectivity (>20:1)