Chloromethylation of arenes

Chloromethylation of arenes. This acid cliloride can be used instead of the suspected carcinogen chloromethyl methyl ether (9 102) for chloromethylation of some arenes. The reaction is conducted in CH,NOi or t S, under standard Friedel-Crafts conditions (AlCl, catalysis). This chloromethylation is particularly useful for aryl ethers substituted in the o- or p-position by an electron-v, ithdrawing group (yields —50-90%). 

CUorometkyltition. Olah and co-workers have reported furtho studies arenes with these reagents. The reaction shows a wide range of selectivities with variation in conditions. 

A polymer-bound analog of the p-sulfonato-calix[6]arenes is described in a Shinkai patent [31,32], which states that the hexakis(carbetoxymethyl)ether of p-sulfonatocalix[6]arene was partially nitrated, ami-nated, and fixed on crosslinked chloromethylated polystyrene. This resin is stated to absorb 108 ixg of uranium... 

Recently, Deligoz and Yilmaz [51] prepared three polymeric calix[4]arenes, which were synthesized by reacting chloromethylated polystyrene with 25,26,27-tribenzoyloxy-28-hydroxy calix[4]arene (2a, 3a) and po-lyacryloyl chloride with 25,26,27,28-tetraacetoxy ca-lix[4]arene (4a). After alkaline hydrolysis of the polymers, they were utilized for selective extraction of transition metal cations from aqueous phase to organic phase. 

To support a polystyrene onto the upper rim of ca-lix[4]arene (phenolic-O- of calix[4]arene) and 25,26,27-tribenzoyloxy-28-hydroxy, calix[4]arene was treated with chloromethylated polystyrene in the presence of K2CO3 (Scheme 7). Polymeric calix[4]arene (3a) thus obtained was hydrolyzed in the benzoyl groups prior to use for the extraction process. 

Chloromethylation is a useful method for substitution of —CFI2C1 for an aromatic hydrogen, provided one starts with a reasonably reactive arene. The reagents are methanol and hydrogen chloride in the presence of zinc chloride ... 

This reaction, which is comparable to a Friedel-Crafts Alkylation, is useful for the preparation of chloromethylated arenes (for example, the Merrifield resin based on polystyrene) from the parent arene with formaldehyde, HC1, and ZnCl2. 

The Lewis acid ZnCl2 effects formation of an oxonium ion which is reactive in electrophilic aromatic substitution. The intermediate zinc alkoxide reacts with the arene to form the chloromethylated product and zinc oxides ... 

Direct alkylation of Dep-protected dipropylenetriamine by bis(chloromethyl)arenes led to aryl-containing macrocycles in high yields. The protecting phosphate moiety can be easily cleaved under acidic conditions giving macrocycles 38 and 39 (Scheme 4) <2000HCA793>. 

Arene-containing 18-membered tetraazamacrocycle 98 (Equation 6) was prepared by [2+2] cyclization of substituted ethylenediamine and l,3-bis(chloromethyl)benzene in 14% yield as well as 99 formed by a [3+3] reaction (4%) <2006TL2371>. 

Apart from their behaviour as ligands in metal catalyst systems, studies of the reactivity of phosphites towards a wide variety of other substrates have attracted attention. New aspects and applications of the classical Michaelis-Arbuzov reaction and its variants continue to appear. Evidence of the thermal disproportionation of methyltriaryloxyphosphonium halides formed in the reactions of triarylphosphites with alkyl halides, together with the formation of P-O-P intermediates, has been reported. The Michaelis-Arbuzov reaction has been used in the synthesis of phosphonate-based styrene-divinylbenzene resins and polyphosphonated chelation therapy ligands.Treatment of electron-rich benzylic alcohols dissolved in triethylphosphite with one equivalent of iodine affords a low-temperature one-pot route to the related benzylic phosphonates, compounds which are otherwise difficult to prepare. Upper-rim chloromethylated thiacalix[4]arenes have also been shown to undergo phosphonation on treatment with a phosphite ester in chloroform at room temperature. The nickel(II)-catalysed reaction of aryl halides with phosphite esters in high boiling solvents, e.g., diphenyl ether, (the Tavs reaction), has also... 

Chloromethyl groups are an obvious starting point for the introduction of further functions, e.g. via the Arbuzov reaction. Bidentate A-donor groups were introduced by nucleophilic substitution with suitable diamines . Especially interesting is the intramolecular bridging of adjacent phenolic units by reaction with bis-nucleophiles. Thus, derivatives with C2 symmetry have been obtained from chloromethylated calix[4]arenes , while a... 

Compound 200e provides one example in which a pair of calixarenes are intermolecularly joined by a pair of upper rim to lower rim bridges. Other examples of upper rim to upper rim bridging are illustrated by (a) 215a, obtained in 48% yield by treating p-A,C-bis(hydroxymethyl)calix[4]arene with p-A,C-bis(chloromethyl)calix[4]arene in the presence of (b) 215b and... 

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