Demethylation of crown ethers, aza crown ethers, and cryptands which have inward‐facing anisole units by lithium aluminum hydride in tetrahydrofuran

Czech, Anna; Czech, B.; Desai, Dhimant; Hallman, Johnny L.; Phillips, John B.; Bartsch, Richard A.

doi:10.1002/jhet.5570230518

Cited by 7 publications

(1 citation statement)

References 19 publications

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“…Attempts to use cations other than lithium (Table , entries 15−17) were to no avail. Bartsch et al have reported the use of LiAlH 4 in refluxing THF for deprotection of aryl methyl ethers incorporated in oxocrown ethers . Unfortunately, no reaction was obtained using these conditions (Table , entries 18 and 19).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Enantiomerically Pure Thiocrown Ethers Derived from 1,1‘-Binaphthalene-2,2‘-diol

Stock

Kellogg

1996

J. Org. Chem.

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Synthetic methodology is given for the preparation of two different types of thiocrown ethers from optically pure 1,1′-binaphthalene-2,2′-diol (10). The conceptually simplest approach starts from optically pure 10 itself, which is alkylated (4 equiv of K 2 CO 3 in DMF at 110°C) with 2-chloroethanol followed by mesylation to provide 2,2′-bis(2-(mesyloxy)ethoxy)-1,1′-binaphthyl (14). When allowed to react with ethane-1,2-dithiol, propane-1,3-dithiol, 1,4,7-trithiaheptane, 1,4,8,11-tetrathiaundecane, 2,2-dimethylpropane-1,3-dithiol, 2-(mercaptomethyl)-1-propene-3-thiol, and 1,2-benzenedithiol in the presence of Cs 2 CO 3 in DMF at 60°C the corresponding thiocrown ethers 22-25, 28, 30, and 32 are formed in 30-54% yields. Test reactions were carried out to establish that no racemization occurs during alkylation under these conditions. Reaction of optically pure 10 with tetrahydropyranyl (THP)-protected 3-chloropropanol under similar conditions for the preparation of 14 proceeded more sluggishly but cleanly. Removal of the THP protecting groups afforded 2,2′-bis-(3-bromopropoxy)-1,1′-binaphthyl (20), which on reaction with propane-1,3-dithiol, 1,5,9-trithianonane, 2,2-dimethylpropane-1,3-dithiol, 2-(mercaptomethyl)-1-propene-3-thiol, and 1,2-bis(mercaptomethyl)benzene provided the respective thiocrown ethers 26, 27, 29, 31, and 33 in 24-68% yields. Another class of thiocrown ethers was prepared from optically active 10, which was converted via ortholithiation to 3,3′-bis(bromomethyl)-2,2′-dimethoxy-1,1′-binaphthyl (39) by means of methylation (K 2-CO 3 /CH 3 I), ortho-lithiation followed by formylation (n-C 4 H 9 Li/N,N,N′,N′-tetramethylethylenediamine (TMEDA)/ether followed by DMF and H 2 O workup) followed by reduction (NaBH 4) followed by bromination (PBr 3 in C 5 H 5 N). Reaction (Cs 2 CO 3

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Section: Resultsmentioning

confidence: 99%

Synthesis of Enantiomerically Pure Thiocrown Ethers Derived from 1,1‘-Binaphthalene-2,2‘-diol

Stock

Kellogg

1996

J. Org. Chem.

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ChemInform Abstract: Demethylation of Crown Ethers, Aza Crown Ethers, and Cryptands Which Have Inward‐Facing Anisole Units by Lithium Aluminum Hydride in Tetrahydrofuran.

Czech

Desai

et al. 1987

ChemInform

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Pyridinium N‐Phenoxide Betaines and Their Application to the Characterization of Solvent Polarities, XX. – Synthesis, Solvatochromism, and Halochromism of Chromoionophoric Crown Ether‐substituted Pyridinium N‐Phenolate Betaine Dyes

1993

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Synthesis, negative solvatochromism (Table 1, Figure l), and negative halochromism (Tables 2 -3, Figures 2 -3) of the new crown ether-substituted pyridinium N-phenolate betaine dyes 3 -6 are described. In contrast to other known chromoionophores, 3 -5 exhibit a cation-selective negative halochromism, which manifests itself as a hypsochromic shift of the longwavelength intramolecular charge-transfer (CT) absorption band of the betaine chromophore on addition of salts. As this The position of the longest-wavelength absorption band in the UV/Vis solution spectra of the pyridinium N-phenolate betaine dye 1 depends on the polarity of the solvent (solvatochromism), the temperature of the solution (thermochromism), the external pressure applied to the solution (piezochromism), the nature and concentration of added salts (halochromism), and possibly -in the case of chiral betaine dyes -on the configuration of enantiomerically pure, homochiral solvents (chiro-solvatochromism)~4~51. The unusually large negative solvatochromism of 1 has been used to introduce spectroscopically derived empirical parameters of solvent polarity, the so-called ET (30) It has been shown['.'71 that the salt-induced negative halo~hromism['~] of 1 and 2 stems mainly from an ion-pairing between the cation, delivered from the salt added, and the phenoxide part of the betaine dye. There is even a linear correlation between the halochromic band shifts and the charge-to-size ratio (effective charge) of the cations, at least in acetonitrile as solvent ['.'41. This cation-influenced negative halochr~rnism~'~~ should be enhanced and made more cation-selective by the introduction of crown ether rings into the phenolate moiety of 1. For this reason, we have synthesized und UV/Vis-spectroscopically studied the new chromoionophoric[''] betaine dyes 3 -6, which have several advantages over the chromoionophoric dyes known to CT absorption band lies within the visible spectral region, the cation-induced colour change can b e followed easily by eye, which suggests an application of these new chromoionophoric betaine dyes as cation indicators. The halochromism of 3-6 constitutes a new type of true halochromism, in contrast to the trivial halochromism first defined by Baeyer and Villiger in 1902. date[*". The crown ether-substituted betaine dyes 3 -6 possess cavities capable of binding suitable guest species such as alkaline metal cations by means of ion/dipole interactions -with concomitant colour changes in the visible spectral range as desirable result. Because the intensity of the longwavelength charge-transfer (CT) absorption band of 1 [**] (and of 2-5) is rather low ( E ca. 300-800 1 . mol-' . cm-'),

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Demethylation of crown ethers, aza crown ethers, and cryptands which have inward‐facing anisole units by lithium aluminum hydride in tetrahydrofuran

Abstract: Lithium aluminum hydride in tetrahydrofuran is an efficient demethylating reagent combination for mono‐ and bicyclic polyether compounds which bear intra‐annular methoxyaryl groups.

Cited by 7 publications

References 19 publications

Synthesis of Enantiomerically Pure Thiocrown Ethers Derived from 1,1‘-Binaphthalene-2,2‘-diol

Synthesis of Enantiomerically Pure Thiocrown Ethers Derived from 1,1‘-Binaphthalene-2,2‘-diol

ChemInform Abstract: Demethylation of Crown Ethers, Aza Crown Ethers, and Cryptands Which Have Inward‐Facing Anisole Units by Lithium Aluminum Hydride in Tetrahydrofuran.

Pyridinium N‐Phenoxide Betaines and Their Application to the Characterization of Solvent Polarities, XX. – Synthesis, Solvatochromism, and Halochromism of Chromoionophoric Crown Ether‐substituted Pyridinium N‐Phenolate Betaine Dyes

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