Sodium 2-naphthoxide

The alkylation of sodium 2-naphthoxide with benzyl bromide in tetrabutylam-monium and tetrabutylphosphonium halide salts was investigated by Brunet and Badri [50] (Scheme 5.1-21). The yields in this reaction were quantitative, and alkylation occurred predominantly on the oxygen atom of the naphthoxide ion (typically 93-97 %). The rate of the reaction was slower in the chloride salts, due to the benzyl bromide reacting with chloride ion to give the less reactive benzyl chloride. 

Scheme 5.1-21 The benzylation of sodium 2-naphthoxide with benzyl bromide in ammonium...

Further extensions of the use of pyrylium salts as synthons have appeared for example, their reaction with hydrazines. The xanthyUum salt (27 A = 0) reacted with amines under very mild conditions and in good yield and it has been used to synthesize sulphones, sulphides, and ethers in the presence of phase-transfer catalysts for example, 2-hexyloxynaphthalene was obtained in 70% yield by heating the acridinium salt (27 A = NC Hia) with sodium 2-naphthoxide and Bu4N A phase-transfer catalyst has... 

Sodium 2-naphthoxide (from NaH) in THF added to 1,3-bis(tert-butyldimethylsiloxy)propyl-2-yl 2,5-dichloro-benzensulphonate with 18-crown-6 at ambient, stirred and refluxed (14h) gave the bis(siloxy)prop-2-yl ether (99%)which with MeSO,F added to (Bu)4NF + 4A mol Sieve in THF for 18h at 50° afforded the product. 

Scheme 5.2-57 The benzylation of sodium 2-naphthoxide with benzyl bromide in ammonium or phosphonium halide salts (X = Cl, Br) [127],...

Correlation of phenolate reaction sites with electrophiles is as valid as in the other ambident systems. Thus, only the methyl ethers are produced from the reaction of sodium 2,6-dimethylphenoxide with methyl brosylate (181) or sodium 2-naphthoxide with dimethyl sulfate (182). Analysis of aroyl-ation of 2-naphthoxides in hexane (183) indicates that (0 softer Li enolate gives higher C/O ratios than the Na enolate, and (//) more C-acylation occurs with the aroyl chloride of softer nature. 

The phase transfer method has also been used in the preparation of a variety of phenolic ethers [5]. It is interesting that alkylation of phenoxide anions generally yield products of both C and 0-alkylation with one favored to a greater or lesser extent depending on solvent. Sodium 2-naphthoxide, for example, exclusively C-benzylates in such hydrogen bonding solvents as ethanol [6], whereas 0-alkylation is favored in tetrahydrofuran. As the size of the cation associated with 2-naphthoxide is increased (for example from Li" to R4N ), 0-alkylation tends to be favored. Consistent with these observations is the report that 2-naphthol 0-alkylates under phase transfer conditions [5]. The successful 0-alkylation of the isomeric nitrophenols and salicyl-aldehyde are also noteworthy. These observations are consistent with the view that... 

The mesylate was then displaced using sodium naphthoxide made from 8 with base. The silyl group is not wanted in the final product and was removed with TBAF (tetrabutylammonium fluoride, Bu4N+ F ). Finally the epoxide 10 was opened with isopropylamine 11. This synthesis depends on regioselective opening of an epoxide at the less substituted end. 

Reduction of the sodium salt of equilenin 17-ethylene ketal with lithium, sodium or potassium in ammonia at —70° occurs predominantly in the B-ring, affording, after acid hydrolysis, equilin (29) in up to 76% yield (55% isolated). The preferential reduction of the B-ring reflects the relative, but not absolute, resistance to reduction conferred on the A-ring by the naphthoxide ion. Some A-ring reduction does compete kinetically with B-ring reduction, since the epimeric 3-hydroxyestra-5,7,9-trien-17-ones are the major reaction by-products. Simple phenoxide ions usually reduce slowly... 

Alkoxide or aryloxide anions are also reputed to be inactive in Sr I reactions. There is, however, one example of such a reaction at an sp carbon the nitro-derivative of 4-nitrocumyl reacts with phenoxide and 1-methyl-2-naphthoxide ions yielding the corresponding ethers (Kornblum et al., 1967). A similar reaction has been reported for halobenzenes in t-butyl alcohol upon stimulation by sodium amalgam (Rajan and Sridaran, 1977). This reaction could not, however, be reproduced (Rossi and Pierini, 1980) and other attempts to make phenoxide ions react at sp carbons have been equally unsuccessful (Ciminale et al, 1978 Rossi and Bunnett, 1973 Semmelhack and Bargar, 1980). It has been found, more recently, that phenoxide ions react with a series of aryl halides under electrochemical induction, but that the coupling occurs at the p- or o-phenolic carbon rather than at the phenolic oxygen (Alam et al, 1988 Amatore et al, 1988). This is... 

The advantages of the catalyzed version are particularly apparent in the case of allyl alcohol whose epoxide, glycidol (2), is unstable to the catalyst.2 It can be obtained by catalyzed epoxidation at 0° with cumene hydroperoxide instead of t-butyl hydroperoxide in 65% yield and 90% ee. However, for use in a synthesis of the P-adrenergic blocking agent (2S)-propranolol (5), the epoxide is not isolated but treated with sodium a-naphthoxide to furnish the diol 3. The synthesis of 5 is completed by conversion to an epoxide (4) and ring opening with isopropylamine. 

This idea was realized very successfully by Shibasaki and Sasai in their heterobimetallic chiral catalysts [17], Two representative well-defined catalysts. LSB 9 (Lanthanum/Sodium/BINOL complex) and ALB 10 (Aluminum/Lithium/BINOL complex), are shown in Figure 8D.2, whose structures were confirmed by X-ray crystallography. In these catalysts, the alkali metal (Na, Li, or K)-naphthoxide works as a Br0nsted base and lanthanum or aluminum works as a Lewis acid. 

Thiophosgene (1.15 g, 0.01 mol) in chloroform (40 ml) was slowly treated at room temperature with sodium l,4-methano-l,2,3,4-tetrahydro-6-naphthoxide (1.82 g, 0.01 mol). After 30 minutes, N-methyl-m-toluidine (2.42 g, 0.02 mol) in chloroform (40 ml) was added dropwise to the solution so obtained at room temperature. The reaction mixture was stirred for 48 hours at room temperature and then refluxed for 2 hours. The solvent was evaporated, and the residue redissolved in water and extracted repeatedly with diethyl ether. The organic phase was dried (Na2S04) and evaporated to... 

Chlorobiphenyl and 2-chloronaphthalene were irradiated in methanol containing / -naphthol and sodium methoxide and found to undergo photodechlorination408. The key step in the mechanism is electron transfer from photoexcited naphthoxide anion 133 to the aryl halide. The naphthoxyl radical is supposed to take up a hydrogen atom from the solvent and, by subsequent deprotonation, the naphthoxide anion is regenerated (equation 111). 

An undissociated diazonium hydroxide is not necessary for coupling since benzenediazonium chloride couples readily with either /3-naphthol or sodium /3-naphthoxide in anhydrous pyridine solution.96... 

Chloro-l-hydroxynaphthalene is converted into the sulphonate 246 on eosin-sensitized irradiation in the presence of sodium sulphite. A study of the chain substitution of the chloro group in 4-chloro-l-hydroxynaphthalene by aqueous sodium sulphite has shown that two mechanisms for the photoinitiation have been identified and two intermediates have been detected a radical anion of 4-chloro-l-naphthoxide and the sulphite radical anion. Thus, an SjjajI mechanism is suggested and is one that involves reaction with the radical anion of sulphite. An example of the S n 1 process between a phenol and the (2-cyanoaryl)azo-f-butylsulphides has been reported. The 1 reactivity of several compounds (Scheme 27) have demonstrated that 247 is a product however, this is also photochemically reactive and is converted into the cyclic ether 248 . 

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