141208-06-2Relevant articles and documents
Photocatalytic e → Z Isomerization of β-Ionyl Derivatives
Livingstone, Keith,Tenberge, Marius,Pape, Felix,Daniliuc, Constantin G.,Jamieson, Craig,Gilmour, Ryan
supporting information, p. 9677 - 9680 (2019/11/29)
An operationally simple E → Z isomerization of activated dienes, based on the β-ionyl motif intrinsic to retinal, is reported using inexpensive (-)-riboflavin (vitamin B2) under irradiation at 402 nm. Selective energy transfer from photoexcited (-)-riboflavin to the starting E-isomer enables geometrical isomerization. Since the analogous process with the Z-isomer is inefficient, microscopic reversibility is circumvented, thereby enabling a directional isomerization to generate the contra-thermodynamic product (up to 99% yield, up to 99:1 Z/E). Prudent choice of photocatalyst enables chemoselective isomerization to be achieved in both inter- and intramolecular systems. The principles established from this study, together with a molecular editing approach, have facilitated the development of a regioselective isomerization of a truncated triene based on the retinal scaffold.
Copper-Catalyzed Asymmetric Conjugate Addition of Dimethylzinc to Acyl-N-methylimidazole Michael Acceptors: A Powerful Synthetic Platform
Drissi-Amraoui, Sammy,Morin, Marie S. T.,Crévisy, Christophe,Baslé, Olivier,Marciadefigueiredo, Renata,Mauduit, Marc,Campagne, Jean-Marc
supporting information, p. 11830 - 11834 (2015/10/05)
An efficient copper-catalyzed enantioselective conjugate addition of dimethylzinc to α,β- and α,β,γ,δ-unsaturated 2-acyl-N-methylimidazoles has been achieved using a chiral bidentate hydroxyalkyl-NHC ligand. The reactions proceeded with both excellent regio- and enantioselectivity (14 examples, 87-95 % ee) to afford the desired 1,4-adducts, which were easily transformed to the corresponding aldehydes, esters, and ketones. Subsequently, this powerful methodology was therefore successfully applied in the synthesis of natural products. Furthermore, an iterative process was also disclosed leading to highly desirable 1,3-desoxypropionate skeletons (up to 94 % d.e.). The enantioselective conjugate addition of dimethylzinc to (poly)unsaturated 2-acyl-N-methylimidazoles proceeds under Cu catalysis with excellent regio- and enantioselectivities (up to 95 % ee). The resulting 1,4-adducts can be easily transformed to the corresponding aldehydes, esters, ketones, and amines. This methodology was successfully applied in the synthesis of 1,3-desoxypropionate subunits and natural products.
Retinoids and related compounds. Part 22. Synthesis of β-ionone analog tricarbonyliron complexes
Wada, Akimori,Fujioka, Naoko,Ito, Masayoshi
, p. 171 - 176 (2007/10/03)
The synthesis of β-ionone analog tricarbonyliron complexes was investigated. N-Methoxy-N-methyl-(2,6,6-trimethyl-1-clohexen-1-yl)-2- propenamide (Weinreb amide), prepared from the corresponding ethyl ester and N,O-dimethylhydroxylamine hydrochloride, reacted smoothly with various organometallic reagents to afford the β-ionone analogs in good to excellent yields. Treatment of these compounds with dodecacarbonyltriiron afforded the corresponding tricarbonyliron complexes in high yields.
Synthesis of (12,13-(13)C2)retinal and (13,14-(13)C2)retinal: a strategy to prepare multiple-(13)C-labeled conjugated systems
Groesbeek, M.,Rood, G. A.,Lugtenburg, J.
, p. 149 - 154 (2007/10/02)
(12,13-(13)C2)Retinal, (13,14-(13)C2)retinal, (19-(13)C)retinal and (20-(13)C)retinal (1) were prepared in a simple fashion in high yield via a consecutive strategy.The key step is the reaction of a N-methoxy-N-methylamide with an alkyllithium or a Grignard reagent.The preparation of the required N-methoxy-N-methylamide is discussed.In this scheme, only three commercially available (13)C-labeled starting materials (ethyl bromoacetate, acetonitrile and methyl iodide) are sufficient to construct retinals with any possible combination of (13)C labeling in the conjugated tail end.This strategy is applicable to the preparation of many other conjugated systems, such as retinoids, carotenoids and polyenes.
