Synthesis of lariat ether carboxylic acids based on dibenzo‐16‐crown‐5

Abstract

Synthetic routes to forty‐seven dibenzo‐16‐crown‐5 compounds with pendant carboxylic acid groups are reported. When taken together with previously described lariat ether carboxylic acids, these new compounds provide several series with systematic structural variations including changes in the identity and attachment site(s) of one or more lipophilic groups and the length of the spacer that connects the carboxylic acid group to the polyether framework.

Synthesis of C‐pivot lariat ethers

“…Hydroxymethyl lariat ethers 535a , 535b were synthesized as outlined in Scheme [58, 97]. Vinylidene dibenzo‐crown ethers 534a , 534b were prepared in 72–74% yield by cyclization of bisphenols 456 and 533 with methallyl dichloride and cesium carbonate in acetonitrile.…”

“…Using both approaches, Bartsch et al . [75, 89, 94, 97, 101–104] reported the synthesis of lipophilic lariat ether carboxylic acids in which the lipophilic group is incorporated either into the sidearm or on the geminal carbon.…”

“…Similarly, were prepared lariat carboxylic acids with lipophilic groups at both the geminal position and on the sidearm [97].…”

“…Dibenzo lariat ether carboxylic acids with substituents on both benzene rings were prepared by two methods. In the first method, the appropriate lariat ether alcohol containing the ring substituents were reacted with NaH and then bromoacetic acid to give the target lariat ethers [91, 97]. In the second method, nitro‐ and sulfonic acid groups were introduced into the benzene rings of the preformed lariat ether carboxylic acid by nitration and sulfonation, respectively.…”

Sterically congested, geminal aryl-substituted, proton-ionizable sym-dibenzo-16-crown-5 lariat ethers: synthesis and alkali metal cation extraction

“…This was unusual since similar reactions reported in literature always gave esters. [13][14] Protonation of the lariat ether carboxylate gave the target lariat ether carboxylic acid 19 in 91% yield. As described earlier, the carboxylic acid 19 was converted into the corresponding acid chloride 20 by reaction with oxalyl chloride in benzene followed by reaction of the crude acid chloride with the appropriate sodium sulfonamide in THF to produce the proton-ionizable sym- (9-phenanthryl) For each of the three series of compounds with N-(X)sulfonyl oxyacetamide functional side arms, the carbonyl group IR absorption increased in wavenumbers as the electron-withdrawing ability of X was enhanced in the order Me ≤ Ph < C 6 H 4 -4-NO 2 < CF 3 ( Table 1).…”