Solid‐State Regioselective Cyclization Initiated by the Electrophilic Attack on the Double Bond by N‐Bromosuccinimide on Montmorillonite K‐10 Clay Support under Microwave Irradiation
作者:K. C. Majumdar、H. Rahaman、B. Roy
DOI:10.1080/00397910701228992
日期:2007.5
3-AllyI-4-hydroxy-coumarins and pyrones were regioselectively cyclized with N-bromosuccinimide (NBS) on solid phase under microwave irradiation in excellent yield. NBS on montmorillonite K-10 clay under microwave irradiation for expeditious solvent-free regioselective cyclization has been used for the first time.
Regioselective Synthesis of 4,5-Dihydro-6<i>H</i>
-oxepino[3,2-<i>c</i>
]chromene-2,6(3<i>H</i>
)-diones through Palladium-Catalyzed Intramolecular Alkoxycarbonylation of 3-Allyl-4-hydroxycoumarins
作者:D. Oliver Sosa、Karla Almaraz、Manuel Amézquita-Valencia
DOI:10.1002/ejoc.201900649
日期:2019.8.7
This work presents a regioselective route to synthesize seven‐membered ring lactones fused to coumarin scaffold in good yields and high regioselectivity. Additionality, the carbonylation reaction does not require acidic conditions and proceeds in the absence of any other additive such as hydrogen (H2).
<i>N</i>-Iodosuccinimide: An Efficient Reagent for Regioselective Heterocyclization of 3-Allyl-4-hydroxy[1]benzopyran-2-ones
作者:K. C. Majumdar、P. K. Basu、B. Roy
DOI:10.1081/scc-120024750
日期:2003.10
Abstract Thermal Claisen rearrangement of 4-allyloxy[1]benzopyran-2-ones in refluxing chlorobenzene gave 3-allyl-4-hydroxy[1]benzopyran-2-ones in 82–90% yield. A number of 3-iodopyrano[3,2-c][1]benzopyran-5(2H)-ones were synthesized in 80–92% yield by the regioselective heterocyclization of 3-allyl-4-hydroxy[1]benzopyran-2-ones with N-iodosuccinimide in acetonitrile at 0–5°C.