A new mode of aromatic metamorphosis has been developed, which allows thiophenes and their benzo‐fused derivatives to be converted to a variety of exotic heteroles. This transformation involves 1) the efficient generation of key 1,4‐dianions by means of desulfurative dilithiation with lithium powder and 2) the subsequent trapping of the dianions with heteroatom electrophiles in a one‐pot manner. Via
The Group 14 (Si, Ge, and Sn), Group 15 (P, As, Sb, and Bi), and Group 16 (Se and Te) 2-trimethylsilyl-1-benzometalloles (7) were prepared by the reaction of the corresponding metal reagents with β, o-dilithio-β-trimethyl-silylstyrene intermediate (6), which was derived from phenylacetylene or o-bromoiodobenzene via three steps. The trimethylsilyl group in 7 could be readily removed by treatment with tetrabutylammonium fluoride to give the C-unsubstituted 1-banzometalloles (10).
siloles is described. The reaction of 1-hydrosilyl-4-silyl-1,3-enynes with diisobutylaluminumhydride (DIBAL-H) gave multisubstituted siloles in good to high yields. This method could be applied to the synthesis of benzosiloles using 2-hydrosilyl-1-(silylethynyl)benzenes as substrates. The silole formation was also promoted even by a substoichiometric amount of DIBAL-H. The reaction provides a straightforward
[reaction: see text] The reaction of (o-silylphenyl)acetylene derivatives with lithium naphthalenide undergoes intramolecular reductivecyclization to produce various silaindene derivatives. On the basis of this methodology, a series of silaindene-containing pi-electron systems are synthesized that show intense blue to greenish-blue fluorescence.
Diisobutylaluminum hydride-promoted cyclization of benzyl and phenylsilyl ethers bearing a 2-(trimethylsilyl)ethynyl group: syntheses of indenes and benzosiloles
proceeds by regio- and stereoselectivehydroalumination of the alkyne moiety followed by intramolecular nucleophilic substitution. o-[2-(Trimethylsilyl)ethynyl]phenylsilyl methyl ethers also underwent the DIBAL-H promoted-cyclization to be converted into 2-(trimethylsilyl)benzosiloles in good yields. This approach provides straightforward and efficient way to construct benzosiloles from readily available