A New and Efficient Synthesis of Coumestan and Coumestrol
摘要:
4-Aryloxy-3-iodocoumarins (4-aryloxy-3-iodo-2H-1-benzopyran-2-one), 4a-c, which are readily available by known procedures starting from 4-hydroxycoumarins 1a,b and diacetoxyiodobenzenes 2a-c; are cyclized with palladium chloride in triethylamine to yield the coumestanes (6H-benzofuran[3,2-c][1]benzopyran-6-ones) 5a-c.
Copper-mediated synthesis of coumestans via C(sp 2 )-H functionalization: Protective group free route to coumestrol and 4′- O -methylcoumestrol
作者:Mayuri M. Naik、Vijayendra P. Kamat、Santosh G. Tilve
DOI:10.1016/j.tet.2017.07.057
日期:2017.9
A simple and efficient two step synthesis of coumestans is described. The key reaction in the synthesis is the use of easily available Cu(OAc)2 for CH functionalization of 3-(2-hydroxyphenyl)coumarin to give coumestan ring system via formal oxidative cyclization. This approach provided a short protective group free route to naturallyoccurring coumestrol and 4′-O-methylcoumestrol.
Smooth Conversion of 3,4-Diarylcoumarins and 3,4,5-Triaryl-2(5<i>H</i>)-furanones to 2<i>H</i>-Chromene and 2,5-Dihydrofuran Derivatives with Dimethyl Sulfide-Borane Complex
作者:Parul Verma、Sangeeta Singh、D. K. Dikshit、Suprabhat Ray
DOI:10.1055/s-1988-27468
日期:——
Reaction of 3,4-diarylcoumarins (3,4-diaryl-2-oxo-2H-1-benzopyrans) and 3,4,5-triaryl- 2(5H)-furanones with dimethyl sulfide-borane complex affords the corresponding 2H-chromenes (2H-1-benzopyrans) and 2.5-dihydrofurans in high yields. 3,4-Diaryl-2(5H)-furanones afford the corresponding furans.
A concise and efficient approach to the syntheses of coumestan analogues has been developed. The underpinning strategy involves a FeCl3-mediated direct intramolecular oxidative annellation of 4-hydroxy-3-phenyl-2H-chromen-2-one derivatives. Utilizing this synthetic protocol, a variety of coumestan derivatives were conveniently obtained from readily available reagents.
A short and elegant synthetic approach for 9-substituted tetrahydro coumestan derivatives and synthesis of some naturally occurring coumestan derivatives
作者:Simra Faraz、Abu Taleb Khan
DOI:10.1039/d4nj02189d
日期:——
corresponding tetrahydro coumestan derivatives by dehydrogenation with DDQ. Moreover, synthesizing naturally occurring coumestan, coumestrol dimethyl ether, and 4-O-methyl coumestrol validated the two-step synthetic route.