phenol as a directing group, high regioselectivity, good substrate scope, mild reaction conditions, and high efficiency. To the best of our knowledge, this is the first example of a regioselective C−H alkenylation of unprotected phenols utilizing phenolic hydroxyl group as a directing group. The alkenylation of unprotected tyrosine and intramolecular cyclization are also successfully carried out under
Cascade Synthesis of 4-Arylcoumarins: Pd-Catalyzed Arylations and Cyclizations with (<i>E</i>
)-Ethyl 3-(2-Hydroxyaryl)acrylates and Triarylantimony Difluorides
The reactions of 3‐(2‐hydroxyaryl)acrylates with triarylantimony difluorides in the presence of Pd(OAc)2 and 2,2'‐bipyridyl under aerobic conditions afforded 4‐arylcoumarins in good‐to‐excellent yields with all of the arylgroups in the triarylantimony difluoride transferred to the coupling products. This protocol increases the synthetic scope of 4‐arylcoumarins, especially those bearing electron‐withdrawing
Phosphine-Catalyzed Synthesis of Highly Functionalized Coumarins
作者:Christopher E. Henry、Ohyun Kwon
DOI:10.1021/ol071181d
日期:2007.8.1
[GRAPHICS]2-Styrenyl allenoates are converted into cyclopentene-fused dihydrocoumarins through phosphine-catalyzed regio- and diastereoselective [3 + 2] cycloadditions. Remarkably, changing the solvent from THF to benzene promotes the conversion of the 2-(2-nitrostyrenyl) allenoate into a tricyclic nitronate through a previously undocumented mode of phosphine catalysis. This nitronate was subjected to efficient face-, regio-, and exo-selective 1,3-dipolar cycloadditions to provide tetracyclic coumarin derivatives.
TETRAHYDROPYRANYLOXY-DIRECTED<i>ortho</i>LITHIATION OF AROMATIC SYSTEMS. SYNTHESIS OF<i>o</i>-HYDROXYCINNAMATE ESTERS FROM PHENOLS
作者:Richard A. Bunce、Joel D. Moore
DOI:10.1080/00304949709355199
日期:1997.6
Harikrishna, G.; Hariprasad, K. Siva; Raju, B. China, Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2021, vol. 60, # 1, p. 111 - 116
作者:Harikrishna, G.、Hariprasad, K. Siva、Raju, B. China、Tiwari, A. K.、Zehra, A.