Telomerization of 1,3‐Butadiene with Carbon Dioxide: A Highly Efficient Process for δ‐Lactone Generation

Abstract

A very efficient and selective telomerization of 1,3‐butadiene with CO2 that leads to the δ‐lactone (3‐ethylidene‐6‐vinyltetrahydro‐2H‐pyran‐2‐one) was obtained using palladium acetate and tris(p‐methoxyphenyl)phosphine as a catalyst in the presence of p‐hydroquinone, N,N‐diisopropylethylamine, and acetonitrile. A high turnover number of 4500 with 96 % selectivity to the δ‐lactone was obtained after 5 h reaction at 70 °C. The reaction was deactivated by the presence of different 1,3‐dialkylimidazolium ionic liquids, possibly by the formation of stable and inactive palladium‐imidazole‐2‐ylidene carbenes.

The Telomerization of 1,3‐Dienes – A Reaction Grows Up

“…In 2017, Beller et al reported a significant improvement in turnover numbers from about 350 to over 1500 using a Pd(0) precursor along with the TOMPP ( L2 , Figure ) ligand . One year later, this number was increased threefold using a combination of Pd/TPMPP ( L5 ) in acetonitrile with p ‐hydroquinone and N , N ‐di‐ iso ‐propylethylamine . Interestingly, attempts to employ N ‐heterocyclic carbenes as ligands or working in imidazolium‐based ionic liquids led to completely inactive catalysts in both cases.…”

Valorization of a CO2‐Derived Lactone by Acyclic Diene Metathesis Polymerization

“…The use of carbon dioxide (CO 2 ) [1] in the synthesis of new molecules [2] has been a subject of interest [3] ever since its successful conversion to cyclic lactones by Inoue and co‐workers, [4] which is largely extended by Behr's group [5] . Among various CO 2 derived lactones, [6] the six‐membered lactone [7] (3‐ethylidene‐6‐vinyltetrahydro‐2H‐pyran‐2‐one or α‐ethylidene‐δ‐vinylvalerolactone: EVV) ( 1 ) is the most acknowledged [8] and investigated precursor [9] owing to its high yield and selectivity [10] . The quantum leap made by Nozaki and co‐workers [11] in achieving the free radical polymerization of ( 1 ) served as a benchmark for the scientific community in developing functionalizable materials [12] .…”

Advances in Palladium-Catalyzed Carboxylation Reactions

“…More recently, various catalytic systems have been developed to perform the telomerization of butadiene with CO 2 to give lactones, including Pd(OAc) 2 in the presence of ferrocenylphosphine ligands, such as 1,1′-bis(diisopropylphosphino)ferrocene (disoppf) [ 70 ], Pd(acac) 2 /PCy 3 [ 62 , 71 ], Pd(acac) 2 /PPh 3 [ 64 ], Pd 2 (dba) 3 /4-(2-(diphenylphosphino)phenyl)morpholine [ 72 ], Pd(acac) 2 /TBAAc (TBAAc = tetrabutylammonium acetate) [ 63 , 73 ], Pd(dba) 2 /TOMPP [TOMPP = tris-( o -methoxyphenyl)phosphine] [ 74 ], and Pd(OAc) 2 /TPMPP/H 2 Q/DIPEA [TPMPP = tris-( p -methoxyphenyl)phosphine, H 2 Q = p -hydroquinone, DIPEA = N , N -diisopropylethylamine] [ 75 ]. In particular, using the last catalytic system, EVL was obtained in 96% selectivity and with an unprecedented TON of ca.…”

“…In particular, using the last catalytic system, EVL was obtained in 96% selectivity and with an unprecedented TON of ca. 4500, by performing the reaction in MeCN at 70 °C for 5 h [ 75 ].…”