Direct imidation of lactones via catalytic oxo/imido heterometathesis

Tungsten Oxide Dispersed on Silica as Robust and Readily Available Oxo/Imido Heterometathesis Catalyst

Continuing our investigation of catalytic oxo/imido heterometathesis as novel water-free method for C=N bond construction, we report here the application of classical transition metal oxides dispersed on silica (MOx/SiO2, M=V, Mo, W) as cheap, robust and readily available alternative to the catalysts prepared via Surface Organometallic Chemistry (SOMC). The oxide materials demonstrated activity in heterometathetical imidation of ketones, WO3/SiO2 being the most efficient. We also describe a new well-defined supported W imido complex (≡SiO)W(=NMes)2(Me2Pyr) (Mes=2,4,6-Me3C6H2, Me2Pyr=2,5-dimethylpyrrolyl) and characterize it with SOMC protocols, which allowed us to identify the position of W on the oxo/imido heterometathesis activity scale (Mo Collapse

Key Words

• imido
• imines
• metathesis
• supported catalysts
• tungsten

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MESH Headings Collapse

Grants

• 19-73-10163 Russian Science Foundation
• 075-00277-24-00 Ministry of Science and Higher Education of the Russian Federation

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Affiliation(s)

Nikolai S Bushkov A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Andrey V Rumyantsev A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia Chemistry Department, Moscow State University, Vorob'evy Gory, 1, 119992, Moscow, Russia
Anton A Zhizhin A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Tatyana V Strelkova A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Roman A Novikov N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prosp., 47, 119991, Moscow, Russia
Evgenii I Gutsul A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Rina U Takazova A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Dinara K Kitaeva A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Nikolai A Ustynyuk A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Pavel A Zhizhko A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia
Dmitry N Zarubin A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov str., 28, 119334, Moscow, Russia

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Readily available Ti-based in situ catalytic system for oxo/imido heterometathesis

We investigate Ti(NEt2)4 supported on silica dehydroxylated at 700 °C as an easily accessible pre-catalyst for oxo/imido heterometathesis reactions. Being activated with TolNH2, the supported Ti amide (SiO)Ti(NEt2)3 (1) demonstrates catalytic activity in the imidation of ketones with N-sulfinylamines comparable with the most active previously described well-defined imido catalyst (SiO)Ti(NtBu)(Me2Pyr)(py)2 (2) (Me2Pyr = 2,5-dimethylpyrrolyl), which implies the in situ formation of surface imido species in this system. The materials obtained via treatment of 1 with anilines (TolNH2 (1a) and p-MeOC6H415NH2 (1b)) were studied with IR, EA and 1H, 13C, 15N and 2D solid-state NMR, although the proposed imido intermediate has not been detected, pointing towards tris-amides (SiO)Ti(NHC6H4X)3 (X = Me, OMe) being the major surface species in the isolated materials 1a and 1b. The system 1/TolNH2 was tested in a range of imidation reactions and demonstrated excellent performance for express high-yielding preparation of ketimines, formamidines, lactone imidates and sulfurdiimines, making it a convenient alternative to the well-defined supported Ti imido catalysts.

Rediscovering Sulfinylamines as Reagents for Organic Synthesis

Sulfinylamines (R-N=S=O), monoaza analogues of sulfur dioxide, have been known for well over a century, and their reactivity as sulfur electrophiles and in Diels-Alder reactions is well-established. However, they have only rarely been used in organic synthesis in recent decades despite the increasing prominence of compounds containing N=S=O functionality, such as sulfoximines and sulfonimidamides. This Minireview aims to bring wider visibility to the unique chemistry enabled by this class of compounds. We focus on advances from the last 10 years, including the first examples of their use in the one-pot syntheses of sulfoximines and sulfonimidamides. Also covered are the reactions of sulfinylamines with carbon-centred radicals, their use for formation of heterocycles through cycloadditions, and catalytic enantioselective allylic oxidation of alkenes via a hetero-ene reaction. These examples highlight the different reactivity modes of sulfinylamines and their underappreciated potential for forming molecules which contain high- or low-valent sulfur, or even no sulfur at all.