Synthesis and Catalytic Activity of Atrane‐type Hard and Soft Lewis Superacids with a Silyl, Germyl, or Stannyl Cationic Center

Abstract

The synthesis and isolation of atrane‐type molecules 1E+ (E=Si, Ge, or Sn) having a cationic group 14 elemental center are reported. The cations 1E+ act as hard and soft Lewis superacids, which readily interact with various hard and soft Lewis basic substrates. The rigid atrane framework stabilizes the localized positive charge on the elemental center and assists the formation of the well‐defined highly coordinated states of 1E+. The cations were applied to the hydrodefluorination, Friedel‐Crafts reaction, alkyne cyclization, and carbonyl reduction as Lewis acid catalysts. Most notably, [1Si][ClO4] exhibits unique chemoselectivity that depends on a solvent in the competitive reaction of silyl enol ether with a mixture of benzaldehyde dimethyl acetal and benzaldehyde. Our findings indicate the potential of hard and soft Lewis superacids in organic synthesis.

Mononuclear organogermanium(iv) catalysts for a [3 + 2] cycloaddition reaction

“…The yield did not rise as the temperature increased beyond 100 °C (Table 1, entry 15). In addition, the effect of the reaction time using 6 mol% catalyst 1 and 100 °C temperature was studied (Table 1, entries [16][17][18]. The reaction was also performed at ambient temperature under solvent-free conditions, and the resulting yield of the product was low (Table 1, entry 19).…”

“…[11][12][13][14][15][16] In recent years, group 14 elements have been used to design and develop a variety of Lewis acid catalysts. [17][18][19] However, tetravalent germanium(IV) catalysts have been scarcely reported in the literature. Initially, Ge(IV) compounds had been chosen as catalysts for polymerization of ε-caprolactone.…”

Intrinsic dynamic and static natures of APn--X+--BPn σ(3c–4e) type interactions (APn = BPn = N, P, As and Sb; X = H, F, Cl, Br and I) in bicyclo[3.3.3] and bicyclo[4.4.4] systems and their behaviour, elucidated with QTAIM dual functional analysis

“…Among a lot of such species, [9][10][11][12][13] the research group of Kawashima demonstrated that 1-hydro-5-carbaphosphatrane and 1-hydro-6-carbaphosphatrane could form an "anti-apicophilic" arrangement. [14][15][16][17] Thus, the skeletons of I and II could supply the diverse electronic structures and have unique functionalities, such as superbase, [18][19][20] catalysis [21][22][23] and biological activity. [24][25][26][27] Alder and coworkers synthesized various derivatives of I and II and related species.…”

Bis(catecholato)germane: an effective catalyst for Friedel–Crafts alkylation reaction

“…[11][12][13][14][15][16] A number of Lewis acid catalysts of group 14 elements have been developed. [17][18][19] However, the Lewis acid catalyst of germanium (IV) is limited in the literature. Recently, substituted catecholate ligands have successfully been employed in the synthesis of germanium(IV) compounds.…”