Unimetal super bases

Unusual Hetarynic Condensation of 3-Bromo-2-ethoxypyridine with Diisopropyl Ketone Enolate in the Presence of a Complex Base

“…Taking into account the results obtained from the arynic condensation of ketone enolates (Caub~re, 1974(Caub~re, , 1978(Caub~re, , 1991(Caub~re, , 1993, the formation of compounds (4) and (5) was expected. The formation of compound (6) was also observed, however, and this is rather unusual.…”

“…In a preceding short communication (Jamart-Gr6goire, lager & Caub~re, 1990), it was established for the first time that ketone enolates are capable of condensation with 3,4-dihydropyridines generated from 3-bromopyridines and appropriate complex bases (Caub~re, 1991(Caub~re, , 1993 to give pyridinyl ketones and pyridinocyclobutenols. In a continuation of our exploration of this new route to pyridine derivatives, we undertook the study of the chemical behaviour of 3-bromo-2-ethoxypyridine in such reactions and found that during its condensation with isopropyl ketone enolate in the presence of the complex base NaNH2.tBuONa, an unusual result was observed (see scheme below).…”

TMP-cadmiate: A Base for Efficient and Chemoselective Deprotonative Metallation Reactions of Aromatic Compounds

“…Due to their electrophilic functional group, N,N- [8a] in THF, an excess of base has to be used. The compatibility of the Cd-Li base (0.5 equiv) with reactive functional groups allowed the expected iodides 3b, 4b and 5b to be formed in good yields (entries [3][4][5]. A ketone function could be tolerated in the reaction, as shown from benzophenone (6a) (entry 6).…”

“…Various (R) n (R') n' MLi (M = metal, R, R' = alkyl, amino, chloro…) type compounds already prepared behave as superbases since such species exhibit behaviours that cannot be reproduced by the monometallic compounds on their own. Among them, LIC-KOR (LIC = (common) butyllithium, KOR = potassium tert-butoxide) first described by Schlosser [3] and Lochmann [4], and BuLi-LiDMAE (DMAE = 2-dimethylaminoethoxide) introduced by Caubère [5] and developed further by Gros and More recently, (R) n (R') n' MLi type compounds with M different from an alkali metal have also been described for their metallation ability by different groups [7]. These species display a large panel of reactivities, depending on both the metal M and the groups connected to it.…”

Sustainable Cyclic Carbonate Production, Utilizing Carbon Dioxide and Azolate Ionic Liquids

“…47 Even though they are more basic than common trialkylamines, the pKa values of their conjugate acids would not warrant them to qualify as superbasic substances. [48][49][50] Nevertheless, their associated anions possess sufficiently high nucleophilicity to attach weakly electrophilic CO2, enabling them to be used in CO2 gas capture and catalysis. 47,[51][52][53][54][55] In this paper, we refer to them as azolate ionic liquids (or salts).…”