Thieme Chemistry Journal Awardees- Where are They Now? An Asymmetric Organocatalytic Sequence towards 4a-Methyl Tetrahydroxanthones: Formal Synthesis of 4-Dehydroxydiversonol
Tricyclic systems generated by an asymmetric vinylogous aldol-oxa-Michael reaction of salicylaldehydes with senecialdehyde were further elaborated using a strategy developed by Tietze et al. to generate 4a-methyl tetrahydroxanthones.
A solvent-free protocol for the synthesis of 3-formyl-2H-chromenes via domino oxa Michael/aldol reaction
作者:Daniela Lanari、Ornelio Rosati、Massimo Curini
DOI:10.1016/j.tetlet.2014.01.110
日期:2014.3
A new solvent-free, TBD-catalyzed protocol for the synthesis of 3-formyl-2H-chromenes is presented. Substituted salicylaldehydes 1 and 3-methyl-2-butenal 2 in the presence of 10 mol % of TBD underwent a domino oxa Michael/aldol reaction to effectively yield the corresponding 2H-chromene derivatives 3. The methodology represents an improvement either in terms of efficiency and sustainability as a small amount of catalyst is required and the work-up procedure is simple and straightforward. (C) 2014 Elsevier Ltd. All rights reserved.
Asymmetric Conjugate Addition of Organozinc Compounds to α,β-Unsaturated Aldehydes and Ketones with [2.2]Paracyclophaneketimine Ligands without Added Copper Salts
作者:Stefan Bräse、Sebastian Höfener
DOI:10.1002/anie.200501732
日期:2005.12.9
Base-Catalyzed Condensation of 2-Hydroxybenzaldehydes with α,β-Unsaturated Aldehydes - Scope and Limitations
The base-catalyzedcondensation of α,β-unsaturated carbonyl compounds with 2-hydroxybenzaldehydes yielding tetrahydroxanthones and dihydrobenzopyrans has been investigated. A novel access to highly functionalized dihydrobenzopyrans via a mild generation of the dienol of senecialdehyde and subsequent conjugated aldol reaction has been reported.
A straightforward synthesis of functionalized 6<i>H</i>-benzo[<i>c</i>]chromenes from 3-alkenyl chromenes by intermolecular Diels–Alder/aromatization sequence
A new and metal-free approach to the synthesis of substituted 6H-benzo[c]chromenes has been developed. This three-step synthetic sequence starts from variously substituted salicylaldehydes and α,β-unsaturated carbonyl compounds to form the chromene core. The de novo ring-forming key step is based on a highly regioselective intermolecular Diels–Alder cycloaddition between 3-vinyl-2H-chromenes and methyl