Synthesis and Application of Siloles: From the Past to Present

Abstract

Heterocyclic compounds in particular siloles in which a carbon atom has been replaced by an isovalent silicon atom, has gained wide attention recently. Due to their unique and interesting electronic and aggregation‐induced emmision properties, they found practical application in many areas. The properties of siloles depend upon the nature of subsituents present on the ring. Therefore, the synthetic methods and strategies continued to evolve since their first synthetic report. The advances in the synthesis of siloles, mechanistic details, substituents effect and applications have been discussed in this review.

Covalent triflates as synthons for silolyl- and germolyl cations

“…Sila-and germacyclopentadienes 1 (siloles and germoles) found widespread interest due to their favorable photophysical properties. [1][2][3][4] Cross hyperconjugation between the ER 2 group and the butadiene part of the heterocycle results in a substantial lowering of the LUMO and an increase of the electron affinity of the group 14 heteroles (tetroles). [5][6][7][8] In addition, the discovery of the aggregation induced emission (AIE) effect of aryl-substituted siloles by Tang and coworker provided a new impetus to this field and had significant impact on materials chemistry.…”

Synthesis of Pyridine-Fused Siloles by Palladium-Catalyzed Intramolecular Bis-Silylation

“…The solvent was then evaporated, and the residue was chromatographed on a silica gel column eluting with hexane-ethyl acetate (10:1) to obtain 0.326 g (17% yield) of 4: HR-MS: calcd for C 15 H 28 NSi 3 : (M + H + )m 306.15241; found, 306.15237. MS m/z 305 (M + ); 1 H NMR δ(CDCl 3 ) 0.09 (s, 9H, Me 3 Si), 0.27 (s, 9H, Me 3 Si), 0.45 (s, 6H, Me 2 Si), 7.17 (dd, 1H, pyridyl-ring proton, J = 7.6, 5.2 Hz), 7.70 (dd, 1H, pyridyl-ring proton, J = 7.6, 2.0 Hz), 8.51 (dd, 1H, pyridyl-ring proton, J = 5.2, 2.0 Hz); 13 (5). In a 300 mL three-necked flask fitted with a stirrer, reflux condenser, and dropping funnel, 1 (2.061 g, 7.15 mmol), bis-(triphenylphosphine)dichloropalladium (0.246 g, 0.351 mmol), and copper(I)iodide (0.068 g, 0.357 mmol) were added to 50 mL of dry triethylamine.…”

“…Thus, new synthetic methods for such compounds have been developed. 1 − 5 Many articles have reported on the transition metal-catalyzed bis-silylation of alkynes with disilane. 6 − 13 Some examples of cis -bis-silylation of internal alkynes with acyclic disilanes have also been reported ( Scheme 1 ).…”

“…Silicon-containing compounds are used in various fields ranging from synthetic organic chemistry to functional materials and pharmaceutical synthesis. Thus, new synthetic methods for such compounds have been developed. − Many articles have reported on the transition metal-catalyzed bis-silylation of alkynes with disilane. − Some examples of cis -bis-silylation of internal alkynes with acyclic disilanes have also been reported (Scheme ). For example, Ozawa et al reported the bis-silylation of Me 3 SiSiF 2 Ph with internal alkynes using a Pd catalyst .…”

Radicals and Anions of Siloles and Germoles

“…Progress in the chemistry of tetroles I , the heavier analogs of cyclopentadiene, is driven by the favorable photophysical properties of these compounds (Figure 1 ). [ 1 , 2 , 3 , 4 ] The cross‐hyperconjugation between the butadiene part and the tetrylene unit lowers their absorption energy and promotes their application in optoelectronic devices. [ 5 , 6 , 7 , 8 ] The discovery of the aggregation induced emission effect in perarylated siloles additionally fueled the interest in this class of compounds.…”