Halides, benzylic, from alcohols reaction

Alkyl halides can be hydrolyzed to alcohols. Hydroxide ion is usually required, except that especially active substrates such as allylic or benzylic types can be hydrolyzed by water. Ordinary halides can also be hydrolyzed by water, if the solvent is HMPA or A-methyl-2-pyrrolidinone." In contrast to most nucleophilic substitutions at saturated carbons, this reaction can be performed on tertiary substrates without significant interference from elimination side reactions. Tertiary alkyl a-halocarbonyl compounds can be converted to the corresponding alcohol with silver oxide in aqueous acetonitrile." The reaction is not frequently used for synthetic purposes, because alkyl halides are usually obtained from alcohols. 

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... 

In addition, the Pd-catalyzed cross-coupHng reactions of compound 46 obtained from ZACA reaction of allyl alcohol have been applied to the syntheses of differently substituted alkenyl, aryl, trimethylsilylethynyl, benzyl, and acyl halides in high yields, as shown in Scheme 3.98 [164]. 

Preparation of Alcohols from the Reactions of Benzylic Manganese Halides with Aldehydes and Ketones (3a-3i)... 

Benzylsamarium complexes display a range of reactivity with various functional groups. Reaction with benzyl halides produces 1,2-diphenylethanes in good yields. Addition of ben-zylsamariums to a wide variety of ketones and aldehydes leads to good yields of alcohols. Reactions of benzylsamarium derived from SmCp2 react with acid chlorides to produce a mixture of alcohols and ketones (Kagan et al., 1993). 

Because of the special structural requirements of the resin-bound substrate, this type of cleavage reaction lacks general applicability. Some of the few examples that have been reported are listed in Table 3.19. Lactones have also been obtained by acid-catalyzed lactonization of resin-bound 4-hydroxy or 3-oxiranyl carboxylic acids [399]. Treatment of polystyrene-bound cyclic acetals with Jones reagent also leads to the release of lactones into solution (Entry 5, Table 3.19). Resin-bound benzylic aryl or alkyl carbonates have been converted into esters by treatment with acyl halides and Lewis acids (Entry 6, Table 3.19). Similarly, alcohols bound to insoluble supports as benzyl ethers can be cleaved from the support and simultaneously converted into esters by treatment with acyl halides [400]. Esters have also been prepared by treatment of carboxylic acids with an excess of polystyrene-bound triazenes here, diazo-nium salts are released into solution, which serve to O-alkylate the acid (Entry 7, Table 3.19). This strategy can also be used to prepare sulfonates [401]. 

Styrene oxides are preferentially attacked by halides at the benzylic position, especially so under acidic reaction conditions. It has been claimed, however, that in water in the presence of cyclodextrins, styrene oxides react with halides to yield exclusively benzylic alcohols [382], Benzylic alcohols can also be obtained from styrene oxides by treatment with halogens in the presence of pyridines [383],... 

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