Directing the Cation Recognition Ability of Calix[4]arenes toward Asymmetric Phase‐Transfer Catalysis

Abstract

The recognition abilities of chiral calixarene hosts toward alkali cation guests have been exploited for the first time in asymmetric phase‐transfer catalysis. The binding affinities of a series of chiral α‐methylbenzylamine‐derived calix[4]arene‐amides toward Na+ guest have been determined by 1H NMR spectroscopic titration experiments. The good apparent association constant values are consistent with the macrocycles' catalytic efficiency in the asymmetric alkylation reaction of N‐(diphenylmethylene)glycine esters under phase‐transfer conditions.

Recent applications of chiral calixarenes in asymmetric catalysis

“…Just recently, Neri et al utilized the cation recognition abilities of calixarene-amides in phase-transfer catalysis [ 40 ]. Seven chiral calix[4]arene derivatives 9–15 ( Fig.…”

A General Method for High-Pressure-Promoted Postfunctionalization of Unclosed Cryptands: Potential Phase-Transfer Catalysts

“…Following General Procedure E using DIPEA (148 μL, 0.85 mmol) the target product was obtained as a white powder (63.8 mg, 52%), following General Procedure D using DIPEA (30 μL, 0.187 mmol) the target product was obtained as a white powder (46. 4 (21). Following General Procedure C using Nmethylmorpholine (75 μL, 0.68 mmol), the target product was obtained as a white powder (89 mg, 76%); following General Procedure D using N-methylmorpholine (21 μL, 0.187 mmol), the target product was obtained as a white powder (206 mg, 90%): mp 247 °C (decomposition); 1 12,16 ]dotriaconta-1(31),12 (32),13,15,27,29-hexaen-31-yl}carbamoyl)methyl]pyridin-1-ium Chloride (24).…”

“…A mong many efficient and versatile onium catalysts developed so far, neutral macrocyclic compounds with an accurate define pocket represent promising phase-transfer catalysts. 1 Although utilization of this type of compound in phase-transfer catalysis (PTC) was introduced by Cram in 1981, 2 the majority of work in this field, however, has pertained exclusively to coronands, 3 calixarenes, 4 and cyclic peptoids, 5 which are hosts for cations. Recently, the cationdependent macrocyclic ion-pair receptor was applied to catalyze the Ritter reaction.…”

Macrocyclic Hosts in Asymmetric Phase-Transfer Catalyzed Reactions

“…We developed this concept for the first time demonstrating the feasibility of enantioselective alkylation of 25a catalyzed by α-methylbenzylamine-derived calix [4]areneamides. 117 We designed derivatives with one to four chiral amide residues; although all the chiral calixarene-amides synthesized proved to efficiently bind the Na + cation, the best ees were observed with catalyst 67, bearing three chiral residues, which promoted the alkylation of 25a with arylmethyl and allyl halides in poor to moderate ees (Scheme 26). Titration experiments and DFT calculation supported the formation of a cone-shaped 1:1 Na + 67 com-…”