626-18-6Relevant articles and documents
Synthesis of Azido-Dienediols by Enzymatic Dioxygenation of Benzylazides: An Experimental and Theoretical Study
Carrera, Ignacio,Gonzalez, David,Martínez, Sebastián,Seoane, Gustavo,Umpiérrez, Diego,Veiga, Nicolás,Vila, María Agustina,de la Sovera, Victoria
supporting information, (2022/03/01)
Allylic azides are versatile structural motifs in organic synthesis because the proximal double bond enables a [3,3]-sigmatropic rearrangement, named as the Winstein rearrangement. In this work, an experimental and theoretical study on the double Winstein rearrangement occurring in azidodienediols derived from the biocatalytic dihydroxylation of substituted benzylazides is presented. Substrates bearing a methyl group at the ortho or meta position produced exclusively rearranged exo-diendiols with the azide group anti to the diol moiety as the major constituent. In the case of para methyl substrates, an equilibrium mixture of rearranged and non-rearranged products was observed, indicating that a full conversion to the exo-dienediols is not possible within this substitution pattern. On the other hand, the presence of a chloro substituent in the diene moiety completely precluded the Winstein rearrangement to take place, giving rise exclusively to the traditional cis-cyclohexadienediols. The observed results were analyzed to determine the mechanistic and kinetic aspects and scope limitations of the reaction as a synthetic tool.
Ruthenium(II) Complex of a Tridentate Azoaromatic Pincer Ligand and its Use in Catalytic Transfer Hydrogenation of Aldehydes and Ketones with Isopropanol
Saha, Tanushri,Prasad Rath, Santi,Goswami, Sreebrata
, p. 1455 - 1461 (2021/05/18)
In this work, a new Ru(II) complex with the redox-active pincer 2,6-bis(phenylazo)pyridine ligand (L) is reported which acts as a metal-ligand bifunctional catalyst for transfer hydrogenation reactions. The isolated complex [(L)Ru(PMe2Ph)2(CH3CN)](ClO4)2; [1](ClO4)2 is characterized by a host of spectroscopic measurements and X-ray structure determination. It is diamagnetic and single-crystal X-ray structure analysis reveals that [1]2+ adopts a distorted octahedral geometry where L binds Ru center in meridional fashion. The observed elongation in the coordinated azo bond length (1.29 ?) is attributed to the extensive π-back bonding, dπ(RuII)→π*(azo)L. The complex [1](ClO4)2 acts as an efficient catalyst, which brings about catalytic transfer hydrogenation reactions of a broad array of aldehydes and ketones in isopropanol and in inert conditions. The selectivity of the catalyst for aldehyde reduction over the other reducible functional groups such as nitro, nitrile, ester etc was also investigated. Mechanistic studies, examined by suitable control reactions and isotope labelling experiments, indicate synergistic participation of both ligand and metal centres via the formation of a fleeting Ru?H intermediate and hydrogen walking to the coordinated azo function of L.
Transfer Hydrogenation of Aldehydes and Ketones with Isopropanol under Neutral Conditions Catalyzed by a Metal-Ligand Bifunctional Catalyst [Cp?Ir(2,2′-bpyO)(H2O)]
Wang, Rongzhou,Tang, Yawen,Xu, Meng,Meng, Chong,Li, Feng
, p. 2274 - 2281 (2018/02/23)
A Cp?Ir complex bearing a functional bipyridonate ligand [Cp?Ir(2,2′-bpyO)(H2O)] was found to be a highly efficient and general catalyst for transfer hydrogenation of aldehydes and chemoselective transfer hydrogenation of unsaturated aldehydes with isopropanol under neutral conditions. It was noteworthy that many readily reducible or labile functional groups such as nitro, cyano, ester, and halide did not undergo any change under the reaction conditions. Furthermore, this catalytic system exhibited high activity for transfer hydrogenation of ketones with isopropanol. Notably, this research exhibited new potential of metal-ligand bifunctional catalysts for transfer hydrogenation.
