Chemoselective Reduction of Some Condensates derived from Chromone-3-carbaldehyde using Sm and Zn
摘要:
Condensates 4-6 undergo reductive dimerization with Sm in THF containing aqueous NH4Cl to produce 7-9, whereas with Zn under similar reaction condition 3-5 produce 10-12.
Metal-Free Cascade Approach toward Polysubstituted Indolizines from Chromone-Based Michael Acceptors
摘要:
An efficient cascade transformation toward indolizine-based molecules has been developed. This process leads to the rapid construction of two C-N bonds and one C-C bond without the need of any metal catalysis. The approach involves easily accessible chromone-based Michael acceptors and propargylamine derivatives as starting materials. This cascade constitutes a novel and very competitive alternative to the well reported strategies using pyridine or pyrrole derivatives for accessing the indolizine ring with substituents at uncommon C-positions
A Mild and Efficient Route to 3-Vinylchromones in Aqueous Micellar Media
作者:Vikash Kumar、Amrita Chatterjee、Mainak Banerjee
DOI:10.1080/00397911.2015.1084008
日期:2015.10.18
A simple, mild, and ecofriendly method has been developed for the synthesis of 3-vinylchromones from 4-oxo-4H-1-benzopyran-3-carboxaldehyde (3-formylchromone) by simple Knoevenagel condensation with various active methylene compounds (AMC) in aqueous micellar media in the presence of catalytic amounts of cetyl trimethylammonium bromide (CTAB) and 1,4-diazabicyclo[2.2.2]octane (DABCO). In the case of malonic acid as AMC, the reaction resulted in formation of only Doebner decarboxylated products under the standard reaction condition. It has been also observed that 3-formylchromone derivatives primarily undergo tandem Knoevenagel and Michael reactions in the presence of >2 equiv. of ethyl acetoacetate to produce benzophenone derivatives, by opening of pyran ring, as the sole product in good yields.
Bandyopadhyay, Chandrakanta; Nag, Partha Pratim; Sur, Kumar Ranabir, Journal of the Indian Chemical Society, 2004, vol. 81, # 2, p. 132 - 136