By the use of an N-heterocyclic carbene copper(I) complex as a catalyst, the boracarboxylation of various alkynes (e.g., diaryl alkynes, aryl/alkyl alkynes, and phenylacetylene) with a diborane compound and carbon dioxide has been achieved for the first time, affording the α,β-unsaturated β-boralactone derivatives regio- and stereoselectively via a borylcupration/carboxylation cascade. Some important reaction intermediates were isolated and structurally characterized to clarify the reaction mechanism.

The catalytic selective multi-component coupling of CO2 , bis(pinacolato)diboron, LiOtBu, and a wide range of aldehydes has been achieved for the first time by using an NHC-copper catalyst. This transformation has efficiently afforded a series of novel lithium cyclic boracarbonate ion pair compounds in high yields from readily available starting materials. This protocol has not only provided a new catalytic process for the utilization of CO2 , but it has also constituted a novel route for the efficient synthesis of a new class of lithium borate compounds that might be of interest as potential electrolyte candidates for lithium ion batteries.

Abstract:The catalytic selective multi-component coupling of CO 2 ,b is(pinacolato)diboron, LiOtBu, and aw ide range of aldehydes has been achieved for the first time by using an NHC-copper catalyst. This transformation has efficiently afforded as eries of novel lithium cyclic boracarbonate ion pair compounds in high yields from readily available starting materials.This protocol has not only provided anew catalytic process for the utilization of CO 2 ,b ut it has also constituted anovel route for the efficient synthesis of anew class of lithium borate compounds that might be of interest as potential electrolyte candidates for lithium ion batteries.The use of carbon dioxide (CO 2 )a saC 1 building block for the synthesis of useful chemicals [1] has received increasing attention from both academia and industry due to its low-cost, easy availability,abundance,nontoxicity,and inherent renewability.[2] However,t he chemical transformations of CO 2 for practical applications remained very limited because of its thermodynamic stability and kinetic inertness.T he synthesis of cyclic carbonates through cyclic addition of CO 2 to epoxides is among the most successful transformations of CO 2 for chemical synthesis ( Figure 1a).[3] Extensive studies in this area have been carried out in the past afew decades,and cyclic carbonates bearing various exocyclic functional substituents have continuously emerged from this approach. [4] Although incorporation of aheteroatom (e.g., aboron atom) into acyclic carbonate framework through reaction with CO 2 could be an attractive method for the construction of an ew type of heteroatom-implanted cyclic carbonate skeleton, such transformation has not been reported previously,p robably because of difficulty in suppressing possible competing side reactions in amulti-component reaction system. Electrolytes[5] play ac ritically important role in lithiumbased rechargeable batteries,w hich have witnessed great progress and awide range of applications in the last decades. [6] Recently,f unctional lithium borate salts, [7] such as lithium bis(oxalato)borate (LiBOB), have attracted intensive interest as electrolytes for high performance lithium batteries, because of their unique properties such as excellent thermal stability,good ionic conductivity,and environmentally benign nature.H owever,t he availability of diversified functional lithium borate salts is quite limited due to the lack of efficient and versatile synthetic methods.For example,the synthesis of aw ater-free lithium borate such as LiBOB with purity that can meet the requirement of battery grade is tedious as it requires not easily accessible precursors and multi-step operations (Figure 1b).[8] Therefore,t he development of efficient and versatile chemical transformations for the synthesis of diverse functional lithium borate salts from easily available starting materials is highly desirable.O nt he other hand, cyclic carbonates such as propylene carbonate and ethylene carbonate are among the most commonly used solvents to dissolve elec...