Cu-Catalyzed Synthesis of 2-Silyl-1,3-butadienes from Allenols and Applications to One-Pot Synthesis of Tetrasubstituted Arylsilanes

A copper-catalyzed chemo- and stereoselective method for the synthesis of (E)-2-silyl-1,3-butadienes from a broad range of allenols using mild Si-B reagents is reported in this study. Our protocol required a short reaction time at ambient temperature to produce the desired dienes in high yields. Synthetic applications are highlighted by the one-pot synthesis of tetrasubstituted arylsilanes from allenols as well as the further functionalization of C-Si bonds.

Copper-Catalyzed Reaction of 2,3-Allenols with Silylzinc Reagents: Access to 2-Silyl-1,3-butadienes

Reaction of 2,3-allenols with PhMe₂SiZnCl or Ph₂MeSiZnCl under catalysis of IPrCuCl or SIPrCuCl was carried out, affording 2-silyl-1,3-butadienes. Secondary and tertiary 2,3-allenols could be used as coupling partners. Reaction of secondary 2,3-allenols gave (E)-2-silyl-1,3-butadienes as the only products.

Palladium-Catalyzed Silylation of 2,3-Allenols with Unactivated Disilanes: Access to 2-Silyl-1,3-butadienes and α-Silyl-β-hydroxy Vinylsilanes

Regioselective silylation of 2,3-allenols with disilanes was carried out under catalysis of Pd₂dba₃/P(o-MeOC₆H₄)₃. In the presence of Cs₂CO₃, the reaction achieved 2-silyl-1,3-dienes. Reaction of 1-aryl-2,3-allenols gave the products with excellent Z/E selectivity and E-isomers as the major species. Reaction of α-alkylallenols or α-alkyl-α-aryl-allenols resulted in products with moderate Z/E selectivity and E-isomers are also major. Without a base, the reaction produced α-silyl-β-hydroxyl vinylsilanes, which were converted to 2-silyl-1,3-dienes upon treatment with Cs₂CO₃.

Highly selective cis-1,4 copolymerization of dienes with polar 2-(3-methylidenepent-4-en-1-yl) pyridine: an approach for recyclable elastomers

We report the coordination copolymerization of a new polar diene-based monomer (MPEP), with isoprene or butadiene. After being quaternized, the resultant materials exhibit remarkable thermal reshaping and recycling properties.

Synthesis of 1,3-Butadiene and Its 2-Substituted Monomers for Synthetic Rubbers

Synthetic rubbers fabricated from 1,3-butadiene (BD) and its substituted monomers have been extensively used in tires, toughened plastics, and many other products owing to the easy polymerization/copolymerization of these monomers and the high stability of the resulting material in manufacturing operations and large-scale productions. The need for synthetic rubbers with increased environmental friendliness or endurance in harsh environments has motivated remarkable progress in the synthesis of BD and its substituted monomers in recent years. We review these developments with an emphasis on the reactive routes, the products, and the synthetic strategies with a scaling potential. We present reagents that are primarily from bio-derivatives, including ethanol, C4 alcohols, unsaturated alcohols, and tetrahydrofuran; the major products of BD and isoprene; and the by-products, activities, and selectivity of the reaction. Different catalyst systems are also compared. Further, substituted monomers with rigid, polar, or sterically repulsive groups, the purpose of which is to enhance thermal, mechanical, and interface properties, are also exhaustively reviewed. The synthetic strategies using BD and its substituted monomers have great potential to satisfy the increasing demand for better-performing synthetic rubbers at the laboratory scale; the laboratory-scale results are promising, but a big gap still exists between current progress and large scalability.

Preparation and property investigation of chain end functionalized cis-1,4 polybutadienes via de-polymerization and cross metathesis of cis-1,4 polybutadienes

The end-functional cis-1,4 polybutadiene displayed improved thermal stability and mechanistic properties.

Stereoselective Copolymerization of Butadiene and Functionalized 1,3-Dienes

[(Mesitylene)nickel(allyl)⁺][BAr^F₄^-] (Ni-1) catalyzes the 1,4-cis selective copolymerization of isoprene and 1,3-butadiene with 15 (RO)₃Si-, R₂N-, RSO₂-, RSO₂NH-, and (RO)₂B-functionalized 1,3-dienes. Incorporation of the functionalized 1,3-diene occurs very efficiently with high comonomer conversions, as observed, for example, for copolymerizations of 1,3-butadiene with (EtO)₃Si(CH₂)₃C(═CH₂)CH═CH₂ (1), PhS(O)₂(CH₂)₃C(═CH₂)-CH═CH₂ (7), or (pinB)C(═CH₂)C(CH₃)═CH₂ (15), while copolymerization rates vary from strongly to slightly decreased when compared to butadiene homopolymerizations.

Highly cis-1,4-selective coordination polymerization of polar 2-(4-methoxyphenyl)-1,3-butadiene and copolymerization with isoprene using a β-diketiminato yttrium bis(alkyl) complex

A novel polar monomer 2-MOPB has been (co)polymerized to afford the highly cis-1,4 regulated P(2-MOPB) and P(2-MOPB-co-IP) of new plastics and rubber depending on the compositions.

α,ω-Bis(trialkoxysilyl) difunctionalized polycyclooctenes from ruthenium-catalyzed chain-transfer ring-opening metathesis polymerization

ROMP/CM of COE using bis(trialkoxysilyl)alkenes CTAs and Ru catalysts affords a series of bis(trialkoxysilyl) difunctionalized polyolefins.