A novel route to substituted 3-methylidenechroman-2-ones and 3-methylchromen-2-ones
摘要:
3-Methylidenechroman-2-ones, or their rearrangement products 3-methylchromen-2-ones, were efficiently synthesized by Michael addition of various nucleophiles to 3-diethoxyphosphorylchromen-2-ones followed by Horner-Wadsworth-Emmons reaction of the adducts with formaldehyde. Relative configuration and conformation of the intermediate adducts were studied using NMR spectroscopy and semiempirical PM3 calculations. (C) 2003 Elsevier Ltd. All rights reserved.
Substituted coumarins as ambident nucleophiles in one-pot hydrogenation/alkylation reaction
作者:Nevena I. Petkova-Yankova、Rositca D. Nikolova
DOI:10.1007/s11696-020-01098-1
日期:2020.8
The regioselectivity of a one-pot hydrogenation/alkylation reaction of coumarins 1a and 1b with series of alkyl halides has been elucidated as a complementary work to reaction of acylation with the same coumarins. Reaction conditions have provided formation of only C-alkylation products with good to high yield. The results from the experiments are of significant importance to predict reactivity of
Catalytic activity of chelating N-heterocyclic carbene palladium complexes towards selective phosphorylation of coumarins
作者:Liangru Yang、Xinchi Zhang、Jinwei Yuan、Yongmei Xiao、Pu Mao
DOI:10.1016/j.jorganchem.2016.06.015
日期:2016.9
The catalyticactivity of a series of heteroaryl coordinated chelating N-heterocyclic carbene (NHC) palladium complexes bearing different N-substituents, NHC backbones and chelating rings towards the phosphorylation of coumarins, and the relationship between the activity and the structure are presented. The results showed that the chelating NHC palladium complex Ia–b bearing the most σ-donating backbone
electron donating substituents on the ring and some coumarins (coumarin, 6-methylcoumarin, 7-methylcoumarin) under the action of dialkyl H-phosphonate (RO)2P(O)H (R = Et, n-Bu, i-Pr), based on catalytic oxidation of arene and H-phosphonate (1:1) mixture in electrochemically mild conditions (room temperature, normal pressure) using the bimetallic catalyst system MnIIbpy/NiIIbpy (1%). This method produces a
A Tandem Conjugate Addition–Intramolecular Horner–Wadsworth–Emmons Olefination Approach to the Synthesis of Cyclopentene[c]chroman-2-ones and Cyclopent-1-enecarboxylates
A strategically newapproach to cyclopentene[c]chroman-2-ones and cyclopent-1-enecarboxylates by tandem Michael–Horner–Wadsworth–Emmons reaction of 2,5-hexanedione with 3-(diethoxyphosphoryl)coumarins is described. The products were obtained as single diastereoisomers in high yields.
The phosphonyl radical generated from the reaction of manganese(III) acetate with diethyl phosphonate selectively adds to the 3-position of flavones and coumarins to afford phosphonylated products in moderate to good yields. manganeseacetate - phosphonylation - flavones - coumarins - dialkyl phosphonate - freeradical