Alkyl -naphthyl ethers

Substitution. Certain alkoxy group of an alkyl naphthyl ether is susceptihle to replacement on reaction with MeMgl under the influence of Ni(II). Interestingly, in the presence of (dppf)NiCl2 the sidechain methoxy group of 6-methoxy-2-naphthylmethyl methyl ether shows a higher reactivity. ... 

Alkyl and aryl-alkyl halides form 2-naphthyl ethers with 2-naphthol. 

Formation of 2 naphthyl ethers. Alkyl halides and aryl-alkyl halides (e.g. benzyl chloride) are converted into 2-naphthyl ethers thus ... 

Picrates of p-naphthyl alkyl ethers. Alkyl halides react with the sodium or potassium derivative of p-naphthol in alcoholic solution to yield the corresponding alkyl p-naphthyl ethers (which are usually low m.p. solids) and the latter are converted by alcoholic picric acid into the crystalline picrates ... 

Mix together 1 0 g. of pure p-naphthol and the theoretical quantity of 50 per cent, potassium hydroxide solution, add 0-5 g. of the halide, followed by sufficient rectified spirit to produce a clear solution. For alkyl chlorides, the addition of a little potassium iodide is recommended. Heat the mixture under reflux for 15 minutes, and dissolve any potassium halide by the addition of a few drops of water. The p-naphthyl ether usually crystallises out on cooling if it does not, dilute the solution with 10 per cent, sodium hydroxide solution untU precipitation occurs. Dissolve the p-naphthyl ether in the minimum volume of hot alcohol and add the calculated quantity of picric acid dissolved in hot alcohol. The picrate separates out on cooling. Recrystallise it from rectified spirit. 

HaUde B.P. M.P.. 20 20 D 1 i. 4nUlde i i a-Naphtha- llde Alkyl 1 Mercuric i Halide S-Alkyl-ito- thiuronlum Picrate Picrate of Q-naphthyl ether... 

Conversion of phenols into their methyl or ethyl ethers by reaction with the corresponding alkyl sulphates in the presence of aqueous sodium hydroxide affords a method which avoids the use of the more expensive alkyl halides (e.g. the synthesis of methyl 2-naphthyl ether and veratraldehyde, Expt 6.111). Also included in Expt 6.111 is a general procedure for the alkylation of phenols under PTC conditions.38,39 The method is suitable for 2,6-dialkylphenols, naphthols and various functionally substituted phenols. The alkylating agents include dimethyl sulphate, diethyl sulphate, methyl iodide, allyl bromide, epichlorohy-drin, butyl bromide and benzyl chloride. 

The simple dialkyl sulphates, in particular dimethyl sulphate, are markedly toxic (see Section 4.2.24, p. 430). They may be characterised as the alkyl 2-naphthyl ethers (cf. alkyl halides, Section 9.6.8, p. 1251 and also Expt 6.111). 

Although mostly alkoxy carbene complexes have been benzannulated, other types of carbene complexes are equally well suited. These include aryloxy carbene complexes as well as acyla-mino and thioalkylidene complexes, and even complexes with no heteroatoms, such as diaryl carbene complexes, are suitable (see below). Besides the commonly used methoxy and ethoxy carbene complexes, alkoxy carbene complexes with a longer alkyl chain have also been successfully reacted. The benzannulation of aryloxy carbene complexes has recently been studied to probe electronic effects [28a]. Aryloxy alkylidene complexes of type 21 have been used to prepare diaryl ethers 22, which constitute a common substructure in many important types of natural products [28b]. The benzannulation methodology provides an access to phenyl naphthyl ethers in yields of 60-93 % under mild conditions (Scheme 11). 

Only two examples will be mentioned here in more detail. The Sn2 alkylation reaction of ambident potassium 2-naphtholate (2-naphthol -I- KOH) with 1-bromobutane in [BMIM]+PF6 at room temperature proceeds at a similar rate as observed in dipolar aprotic solvents such as DMF or DMSO, to regioselectively afford 1-butyl 2-naphthyl ether in 98 cmol/mol isolated yield (0/C alkylation ratio > 99 1) [899]. In contrast to the reaction in dipolar aprotic solvents, which are difficult to remove from the product, the ether product can be simply extracted into an organic solvent such as toluene, leaving the ionic liquid behind. The by-product (potassium bromide) of the reaction can be extracted with water, and the ionic liquid can be used again. 

Alkylation of 4-tert-butylcalix[b]arene has been carried out in 94% yield with triethyleneglycol monomethyl ether 4-tosylate (TsOR) in the presence of benzyltrimethylammonium chloride and potassium hydroxide in chloroform /dichloromethane/methanol solution after stirring for 24 hours at 40°C (ref.42). The synthesis of a number of naphthyl ethers or their further reaction products has been summarised in Table 4.5 (refs.43-46). 

HaUde B.P. H.P.. 20 20 Anilide a-Naphtha- Ude Alkyl Mercuric Halide S-Alkyl-Ao- thluronium Picrate Picrate o( B-naphthyl ether... 

Picrate of alkyl 2-naphthyl ether (Molecular complex). ... 

The picrate is obtained from the alkyl 2-naphthyl ether and picric acid in chloroform or ethanol. 

No Name Boiling point, C "d DP S-Alkyl thiuronium picrate I Naph- ihyl amide Anilide Alkyl mercuric halide Picrate of 2>naphthyl ether 2,4 [>inilro- phenyl ihioeiher 2,4-Dimtro- phenyl sulfone Miscellaneous... 

Scheme 10.14 Photochemical cleavage of I-naphthyl phenylacyl ester 32. A) In hexane. B) In an aqueous solution of poly (alkyl aryl ether) dendrimer G2...

The alkyl 2-naphthyl ether is obtained from the alkyl halide with 2-naphthol in ethanolic sodium or potassium hydroxide. 

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