Binary systems consisting of benzoyl peroxide (BPO) and diorganyl diselenide are effective in the selective benzoyloxyselenation of internal alkynes to afford the corresponding β-(benzoyloxy)alkenyl selenides in good yields. In contrast to internal alkynes, terminal alkynes undergo a novel C(sp)-H substitution with the phenylseleno group of the BPO/(PhSe) system, providing alkynyl selenides in good yields. Both selenation reactions might proceed via benzoyloxy selenide (PhC(O)O-SeAr) as a key intermediate for electrophilic addition to alkynes. The products alkenyl and alkynyl selenides are expected to be useful synthetic intermediates in organic synthesis.
A practical synthesis yielding P‐perfluoroalkylated phosphines from triarylphosphines and perfluoroalkyl iodides has been developed. The photoinduced reaction involves the substitution of aryl groups on the phosphorus atom with perfluoroalkyl groups to successfully afford P‐perfluoroalkylated phosphines. In addition, the P‐perfluoroalkylated phosphines were found to promote the Cu‐free cross‐coupling reaction of acid chlorides with terminal alkynes.magnified image
The functionalization of polysilanes is an important subject in materials science because functionalized polysilanes are expected to exhibit potentially innovative properties. This research aims at the addition of a water-shedding property to polysilanes by introducing perfluoroalkyl groups into their skeleton. The photoinduced iodoperfluoroalkylation of various vinylsilanes takes place successfully upon irradiation with a xenon lamp: vinylmonosilanes undergo iodoperfluoroalkylation with perfluoroalkyl iodides (R f I) regioselectively, and the corresponding perfluoroalkylated silanes are obtained in moderate to high yields. Detailed optimization of the photoinduced iodoperfluoroalkylation has been investigated to apply this method to the functionalization of polysilanes. Polysilanes having vinyl groups can be synthesized by the reductive coupling of dichlorovinylsilanes with samarium diiodide (SmI 2 ) and samarium metal (Sm) upon irradiation with visible light. The synthesized vinylpolysilanes and R f I (about 1.0 mM CHCl 3 solution) are coated on a glass plate sequentially, and then the following photoirradiation with light of a wavelength over 300 nm successfully adds an excellent water-shedding property to the glass plate.
The pinacol coupling is one of the most significant methods to synthesize vic-diols. The combination of samarium diiodide (SmI 2) and samarium metal successfully induces the selective pinacol couplings of not only aromatic aldehydes and ketones but also aliphatic ones in the presence of trimethylchlorosilane (Me 3 SiCl) in 1,2-dimethoxyethane (DME). DME is the most suitable solvent for the reduction system using SmI 2 and Me 3 SiCl. Me 3 SiCl, a widely available additive, prevents the decomposition of the formed vic-diols, i.e., meso-isomers, and controls their stereochemistry. In particular, the pinacol couplings of sterically hindered aliphatic aldehydes and ketones proceed with excellent diastereoselectivities to afford dl-isomers in good yields.
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