81-81-2Relevant articles and documents
Ionic liquids: Efficient media for the lipase-catalyzed Michael addition
Fan, Yunchang,Cai, Dongxu,Wang, Xin,Yang, Lei
, (2018)
Recently, ionic liquids (ILs) have been regarded as ideal media for non-aqueous bio-catalysis. In this work, the synthesis of warfarin by the lipase-catalyzed Michael addition in IL media and the parameters that affected the warfarin yield were investigated. Experimental results demonstrated that the chemical structures of the ILs were a major factor for influencing the warfarin yield. The ILs containing the NTf2– anion were suitable reaction media due to the high chemical stability of this anion. The incorporation of the hydroxyl group on the IL cation significantly improved the lipase activity due to the H2O-mimicking property of this group. The lipase activity decreased by increasing the alkyl chain length on the IL cation due to the non-polar domain formation of the IL cation at the active site entrance of lipase. The ILs and lipase could be reused no less than five times without reduction in the warfarin yield.
Hypervalent Iodine(III)-Mediated Tosyloxylation of 4-Hydroxycoumarins
Xu, Bowen,Gao, Yiping,Han, Jianwei,Xing, Zejing,Zhao, Sihan,Zhang, Ziyang,Ren, Runlin,Wang, Limin
, p. 10136 - 10144 (2019)
An efficient approach was developed for synthesis of 3-tosyloxy-4-hydroxycoumarins under mild conditions by using Koser's reagents. The reaction tolerated various functional groups, and the products served as useful aromatic building blocks. Additionally, a plausible mechanism via iodonium ylide was proposed, and the oral anticoagulant Warfarin was synthesized in good yield.
Primary Amine Catalyzed Activation of Carbonyl Compounds: A Study on Reaction Pathways and Reactive Intermediates by Mass Spectrometry
Bencivenni, Giorgio,Calcaterra, Andrea,Ciogli, Alessia,Iazzetti, Antonia,Mazzoccanti, Giulia,Righi, Paolo,Villani, Claudio
supporting information, (2021/12/01)
The field of organocatalysis is expanding at a fast pace. Its growth is sustained by major stimuli, such as the effort toward an understanding of the mechanisms of reaction and catalytic processes in general, the elucidation of basic properties leading to stereocontrol and the search for broad applicability and scalability of the synthetic methodology. This paper reports a thorough study based on ESI-MS spectrometry of amino-organocatalyzed model reactions under different experimental conditions. Off-line reaction monitoring of mixtures containing different catalytic systems, by ESI-MSn showed the presence of several putative intermediate species, either in their protonated or sodiated forms. In addition, enantioselective chromatography of crude reactions provides the stereochemical outcome of asymmetric reactions. The bulk of the data collected offers a clue of the intricate pathways occurring in solution for the studied reactions.
Enantioselective Michael Addition Reaction Catalysed by Enantiopure Binuclear Nickel(II) Close-Ended Helicates
Arunachalam, Rajendran,Chinnaraja, Eswaran,Natarajan, Ramalingam,Samanta, Krishanu,Subramanian, Palani S.
, (2020/02/04)
The enantiopure Ni(II) helicates [Ni2L1RR.Cl2] (1), [Ni2L1SS.Cl2] (1′), [Ni2L2RR.Cl2] (2), [Ni2L2SS.Cl2] (2′) were synthesized by one-pot self-assembly technique from R-(+)- or S-(?)-1,1′-binaphthyl-2,2′-diamine, with 4-methyl-2,6-diformyl phenol or 4-tert-butyl-2,6-diformyl phenol and nickel salts. This binuclear double stranded Ni(II) helicates were characterized by ESI-MS, IR and single crystal X-ray structure wherever applicable. The extensive chiroptical studies suggest that the complexes are enantiopure in nature. The chirality transfer from ligand L1RR & L2RR to Ni(II) metal centre produced ΔΔ geometrical chirality, while their enantiomeric counterpart L1SS & L2SS produced ΛΛ chirality in their respective complexes.These enantiopure helicates were applied as catalysts in asymmetric Michael addition of 1,3-dicarbonyl compounds with β-nitrostyrene to produce nitroalkanes in good yield (96–98%) and ee (78–94%). (Figure presented.).
First aromatic amine organocatalysed activation of α,β-unsaturated ketones
Sonsona, Isaac G.,Marqués-López, Eugenia,Gimeno, M. Concepción,Herrera, Raquel P.
, p. 12233 - 12240 (2019/08/12)
This work provides an unprecedented example of a chiral aromatic amine used to activate α,β-unsaturated ketones in asymmetric aminocatalysis. Chiral aromatic diamine VII has been efficiently employed, as a proof of concept, in the Michael addition reaction between benzylideneacetones (1a-f) and coumarins (2a-d). The reaction gives rise to warfarin derivatives 3 with promising results using this family of catalysts for the first time. The additional studies performed supported the bifunctional mode of activation of the chiral catalyst VII and the covalent nature of the interactions between the catalyst VII and benzylideneacetones 1.
