Intramolecular cycloaddition of azomethine ylides, from imines of O-acylsalicylic aldehyde and ethyl diazoacetate, to ester carbonyl – experimental and DFT computational study
作者:Amit A. Kudale、David O. Miller、Louise N. Dawe、Graham J. Bodwell
DOI:10.1039/c1ob05867c
日期:——
A series of pentacyclic heterocyclic systems (15 examples, 69–89%) have been synthesized using intramolecular Povarov reactions involving 3-aminocoumarins and O-cinnamylsalicylaldehydes. The Povarov adducts are formed with high selectivity for the trans,trans relative stereochemistry in the newly-formed [6,6] fused ring system. One example of a Povarov adduct featuring a new [6,5] fused ring system is reported. In this case, cis,trans relative stereochemistry was preferred.
A new domino Knoevenagel-hetero-Diels–Alder reaction: an efficient catalyst-free synthesis of novel thiochromone-annulated thiopyranocoumarin derivatives in aqueous medium
An efficient catalyst-free synthesis of novel pentacyclic thiochromone-annulated thiopyranocoumarin derivatives is achieved via domino Knoevenagel-hetero-Diels–Alder reaction of 4-hydroxy dithiocoumarin and O-acrylated salicylaldehyde derivatives in H2O as solvent. The products are formed in good yields with high regio- and stereo-selectivity.
Tributyltin hydride-mediated radical cyclisation of carbonyls to form functionalised oxygen and nitrogen heterocycles
作者:Jon Bentley、Paul A. Nilsson、Andrew F. Parsons
DOI:10.1039/b202077g
日期:2002.6.7
The tributyltin hydride-mediated cyclisation of unsaturated ethers and aminesbearing an aldehyde or α,β-unsaturated ketone group is reported. Cyclisation proceeds via reversible addition of the tributyltin radical to the carbonyl double bond to form an intermediate O-stannyl ketyl. This nucleophilic radical can add intramolecularly to electron-rich double bonds to form substituted 5- or 6-membered
Stereoselective construction of functionalized tetracyclic and pentacyclic coumarinopyranpyrazole/pyrimidinedione/coumarin scaffolds using a solid-state melt reaction
An assembly of tetra / pentacyclic hybrid scaffolds have been synthesized for the first time using a solid-state melt reaction in a stereoselective fashion with excellent yields.
首次使用固态熔融反应以立体选择性的方式合成了一系列四环/五环混合支架。收率极佳。
Discovery of Biologically Optimized Polymyxin Derivatives Facilitated by Peptide Scanning and <i>In Situ</i> Screening Chemistry
Peptides can be converted to highly active compounds by introducing appropriate substituents on the suitable amino acid residue. Although modifiable residues in peptides can be systematically identified by peptide scanning methodologies, there is no practical method for optimization at the “scanned” position. With the purpose of using derivatives not only for scanning but also as a starting point for