Titanium-Mediated Addition of Grignard Reagents to Acyl Cyanohydrins: Aminocyclopropane versus 1,4-Diketone Formation
作者:Paul Setzer、Gwénaël Forcher、Fabien Boeda、Morwenna S. M. Pearson-Long、Philippe Bertus
DOI:10.1002/ejoc.201301251
日期:2014.1
The 1,2-dianion reactivity of the reagent generated from EtMgBr and titanium isopropoxide was illustrated when N-acyl cyanohydrins were used as substrates (>20 examples), giving both aminocyclopropane derivatives and 1,4-dicarbonyl compounds. When the reaction was performed in diethyl ether, 5-hydroxy-1,4-diketones were the main product. Under specific conditions (use of tetrahydrofuran and a bulky
Titanium-Mediated Synthesis of 1,4-Diketones from Grignard Reagents and Acyl Cyanohydrins
作者:Paul Setzer、Alice Beauseigneur、Morwenna S. M. Pearson-Long、Philippe Bertus
DOI:10.1002/anie.201003923
日期:2010.11.8
Double duty: In the presence of titanium isopropoxide, Grignard reagents were found to react with acyl cyanohydrins to give substituted 5‐hydroxy‐1,4‐diketones (see scheme). This new reaction involves a formal addition of a 1,2‐dianionequivalent to both the ester and nitrile moieties.
Abstract The reaction of 2-3- O -isopropylidene- d -glyceraldehyde ( 1 ) with active methylene compounds in the absence of a catalyst involves facile and reversible addition to the formyl group. The adducts are readily transformed into furan derivatives by acid hydrolysis. When the reaction is catalysed with piperidine, unsaturated products are also formed, including α,β- and β,γ-unsaturated dicarbonyl