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
including the particularly simple divinylglycine, which is not easily accessible by using conventional methods. A straightforwardsynthesis of symmetrically α,α-disubstituted α-amino acids is presented. The key step of this process relies on the efficient double addition of Grignard reagents to acyl cyanohydrins to provide N-acyl amino alcohols selectively in good yields. The chemoselectivity of the reaction
The first oxidativecoupling of alkylnitriles with aromatic carboxylicacids using di-tert-butyl peroxide (DTBP) as oxidant was achieved under the catalysis of ionic Fe(III) complexes bearing an imidazolinium cation. This protocol features nontoxic iron catalysis, direct α-C(sp3)–H bond oxidative esterification of alkylnitriles, non-prefunctionalized starting materials, and a broad substrate scope
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.