Summary of main observation and conclusion A regioselective double 1,1-hydrosilylation of terminal aliphatic alkynes with primary silanes catalyzed by one cobalt catalyst has been developed. gem-Bis(dihydrosilyl)alkan...Summary of main observation and conclusion A regioselective double 1,1-hydrosilylation of terminal aliphatic alkynes with primary silanes catalyzed by one cobalt catalyst has been developed. gem-Bis(dihydrosilyl)alkanes containing four silicon-hydrogen bonds are efficiently constructed in an atom-economical man ner. Tolerated substrates include simplest alkyne-ethyne, a complicated drug derivative and various functi on alized terminal aliphatic alkynes. Asymmetric approach using two catalysts is achieved with excelle nt enan tioselectivities to access corresp on ding chiral products. The tra nsformations of Si—H bonds into Si—C, Si—O, and Si —F bonds and the synthesis of enantioriched a-hydroxysilane show synthetic utility.展开更多
Carbonyl sulfide (COS), an analogue of carbon dioxide (CO2), can be converted to CO2 via the carbonic anhydride enzymes widely existing in nature. COS is an ideal monomer for making poly(monothiocarbonate)s, whi...Carbonyl sulfide (COS), an analogue of carbon dioxide (CO2), can be converted to CO2 via the carbonic anhydride enzymes widely existing in nature. COS is an ideal monomer for making poly(monothiocarbonate)s, which are difficult to synthesize by traditional methods. Herein, for the first time, we describe an anionic copolymerization of COS with epoxides using alkali metal alkoxides as the catalysts (initiators), affording poly(monothiocarbonate)s with 100% alternating degree, 〉99% tail-to-head (T-H) content, high number-average molecular weights (Mns, up to 90.3 kg/mol) with narrow molecular weight distributions (D=Mw/Mn, 1.05-1.31 for COS/propylene oxide copolymers) under solvent-free and mild conditions. Oxygen-sulfur exchange reaction (O/S ER), which can result in the production of contaminated dithiocarbonate and carbonate units in the main chain, was nearly completely depressed at 0 ℃. In addition, in contrast to previously reported salen chromium (iron) complexes that required multiple synthetic steps, this work provides simple, low-cost, and effective catalysts for making colorless sulfur-containing polymers.展开更多
基金the National Natural Science Foundation of China(No.21772171)Zhejiang Provincial Natural Science Foundation of China(No.LR19B020001)+1 种基金Zhejiang University K.P.Chao's High Technology Development Foundationthe Fundamental Research Funds for the Central Universities.
文摘Summary of main observation and conclusion A regioselective double 1,1-hydrosilylation of terminal aliphatic alkynes with primary silanes catalyzed by one cobalt catalyst has been developed. gem-Bis(dihydrosilyl)alkanes containing four silicon-hydrogen bonds are efficiently constructed in an atom-economical man ner. Tolerated substrates include simplest alkyne-ethyne, a complicated drug derivative and various functi on alized terminal aliphatic alkynes. Asymmetric approach using two catalysts is achieved with excelle nt enan tioselectivities to access corresp on ding chiral products. The tra nsformations of Si—H bonds into Si—C, Si—O, and Si —F bonds and the synthesis of enantioriched a-hydroxysilane show synthetic utility.
基金X. H. Z gratefully thanks the financial support of the Distinguished Young Investigator Fund of Zhejiang Province (No. LR16B040001) and the National Natural Science Foundation of China (No. 21774108).
文摘Carbonyl sulfide (COS), an analogue of carbon dioxide (CO2), can be converted to CO2 via the carbonic anhydride enzymes widely existing in nature. COS is an ideal monomer for making poly(monothiocarbonate)s, which are difficult to synthesize by traditional methods. Herein, for the first time, we describe an anionic copolymerization of COS with epoxides using alkali metal alkoxides as the catalysts (initiators), affording poly(monothiocarbonate)s with 100% alternating degree, 〉99% tail-to-head (T-H) content, high number-average molecular weights (Mns, up to 90.3 kg/mol) with narrow molecular weight distributions (D=Mw/Mn, 1.05-1.31 for COS/propylene oxide copolymers) under solvent-free and mild conditions. Oxygen-sulfur exchange reaction (O/S ER), which can result in the production of contaminated dithiocarbonate and carbonate units in the main chain, was nearly completely depressed at 0 ℃. In addition, in contrast to previously reported salen chromium (iron) complexes that required multiple synthetic steps, this work provides simple, low-cost, and effective catalysts for making colorless sulfur-containing polymers.