The polyhydroXations, such as polyhydrothiolation and polyhydroamination, of alkynes have been well-established. However, the polyhydroalkoxylation is rarely reported. In this paper, the polyhydroalkoxylation of aromatic diynes was successfully developed in the presence of a superbase, phosphazene base (t-BuP4). A series of soluble and regio-regular anti-Markovnikov additive poly(vinyl ether)s with high molecular weights (Mw up to 40 600) were obtained in high yields (up to 99%). All the polymers are thermally and morphologically stable. The tetraphenylethene (TPE)-containing P1a2a, P1a2b and P1a2c showed unique aggregation-enhanced emission (AEE) characteristics, and their aggregates could be used for explosive detection with a superamplification quenching effect. The poly(vinyl ether)s are degradable under acidic conditions. Thus, this work not only established a new polymerization but also generated a series of functional polymeric materials that are potentially applicable in optoelectronic and biomedical fields.
Xiao-Chao Chen,Kai-Chun Zhao,Yin-Qing Yao,Yong Lu,Ye Liu
The development of an efficient methodology to transform CO2 into valuable chemicals has attracted increasing attention concerning the challenging issues of CO2-utilization. Herein, an efficient approach for the preparation of oxazolidinones from CO2, primary (aliphatic/aromatic) amines and 1,2-dichloroethane (or its derivatives) catalyzed by DBU organo-superbase was achieved with yields of 47–97% under mild conditions (80–100 °C, 12 h, 1.0 MPa CO2). Control experiments demonstrated that the formation of an ion-pair carbamate salt intermediate IS-B derived from the reaction of CO2, DBU (catalyst) and an amine (substrate) was the key step for this three-component reaction. The available DBU–amine–CO2 adduct intermediate (like IS-B-2) with fair stability will evolve into the thermodynamically stable product oxazolidinones upon attack of 1,2-dichloroethane (or its derivatives), along with the regeneration of the DBU catalyst. Alternatively, the decomposition of the DBU–aryl amine–CO2 adduct (like IS-B-1) with relatively poor stability also could result in the competitive substitution reaction of 1,2-dichloroethane (or its derivatives) with the aryl amine. This work provides insights into synergetic CO2-activation by the DBU-catalyst and a nucleophilic amine-substrate via the formation of robust carbamate salt intermediates responsible for the final production of oxazolidinones.
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