Synthesis of Lithium Boracarbonate Ion Pairs by Copper‐Catalyzed Multi‐Component Coupling of Carbon Dioxide, Diboron, and Aldehydes

Abstract

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...

Enantioselective Cyanoborylation of Allenes by N-Heterocyclic Carbene-Copper Catalysts

“…Therefore, the chemo-, regio-, and enantioselective cyanoborylation of allenes still remains a highly attractive research subject for the synthesis of valuable molecules containing multiple synthetically important functional groups, including a chiral nitrile unit, a boryl group, and a CC double bond. During our previous studies on the catalytic addition of copper boryl species to alkynes, 15 aldehydes, 16 and imines, 17 we became interested in the development of selective cyanoborylation of allenes through copper boryl catalysis. Herein, we report a copper-catalyzed chemo-, regio-, and enantioselective cyanoborylation of allenes, which afforded β-boryl allyl nitriles efficiently (Scheme 1B).…”

Wet carbonate-promoted radical arylation of vinyl pinacolboronates with diaryliodonium salts yields substituted olefins

“…Ph 2 I + OTf − 1e was triggered by CO 3 2− to give I, which accelerated radicals 8e and PhI-CO 3 − formed via homo cleavage. The intermediate II formed from vinylboronate 2a and CO 3 2− enabled the addition of radicals 8e to form the C-C bond [45][46][47] , generating the "ate" α-boronate adduct radical species III [48][49][50][51][52] . Species III was capable of occurring SET reaction with radical CO 3 − to give the intermediate moiety IV and intramolecular dehydrocarbonate give the "ate" intermediate VI, which further eliminated to give the desired product 3e.…”

Selective Three-Component Coupling for CO2 Chemical Fixation to Boron Guanidinato Compounds

“…Recently, a comparable selective multicomponent coupling of CO 2 , bis(pinacolato)diboron, LiOt-Bu, and aldehydes to obtain lithium cyclic boracarbonate ion pair compounds has been reported, but an NHC-copper catalyst was required to achieve success. 18 The energetic profile of the reaction with CO 2 was also studied computationally for the borylamine 2 (Figure 5). In the first place, we found that the formation of a hypothetical insertion product of CO 2 into the B−N bond of 2 to form a carbamate compound is an uphill process, with the resulting product being nearly 21 kJ mol −1 above the corresponding starting materials in benzene solution (29 kJ mol −1 in gas phase).…”