Aryl-substituted alcohols, table

Additional clues confirm the radical nature of the reaction of BTNO with RH substrates. A Hammett correlation, obtained on plotting log A h for reaction of BTNO with p-substimted benzyl alcohols, gave a p value of —0.55 vs. a+. This small value, which is reasonable for a radical reaction, compares well with the p values ranging from —0.54 to —0.70 and obtained vs. the same substrates with the aminoxyl radicals generated from X-aryl-substituted HPIs (Table 5). In all cases better Hammett correlations were obtained vs. the values. Hence, a uniform pattern of selectivity emerges among these electrophilic >N—O" species in H-abstraction reactions. 

TABLE 5. NO—H bond dissociation energy values of X-aryl-substituted Ai-hydroxyphthaUmides (X-HPIs), listed with the Hammett p values (vs. ct+) and h/ d ratios obtained in the oxidation of substituted benzyl alcohols using the X-HPIs/Co(II)MCBA/02 system in MeCN solution at 25 °C... 

The formation of 3-aryl-substituted aldehydes and 3-aryl-substituted ketones by the reaction of arylpalladium salts with allylic alcohols is a general reaction.2 Illustrations of the preparation of two aldehydes and two ketones are given in Table I. 

The propargyl alcohols react with trivalent phosphorus halides to give allenic phosphorus esters as described in Scheme 3 and Table VI. In the case of aryl-substituted alkynols or highly hindered t-propargyl alcohols which contain no free acetylenic —H, thionyl halides or phosphorus trihalides yield bromo- or chloroallenes [74d], Thionyl chloride also reacts in a similar fashion with a wide variety of unhindered secondary alcohols (structure XV) to give a mixture of the chloroallene and chloroalkyne [74a-d]. 

The results in Table 3 were explained as shown in Scheme 4. From the fact that no kinetic isotope effect was observed in the reaction of phenyl-substituted disilenes with alcohols (Table 1), it is assumed that the addition reactions of alcohols to phenyltrimethyl-disilene proceed by an initial attack of the alcoholic oxygen on silicon (nucleophilic attack at silicon), followed by fast proton transfer via a four-membered transition state. As shown in Scheme 4, the regioselectivity is explained in terms of the four-membered intermediate, where stabilization of the incipient silyl anion by the phenyl group is the major factor favoring the formation of 26 over 27. It is well known that a silyl anion is stabilized by aryl group(s)443. Thus, the product 26 predominates over 27. However, it should be mentioned that steric effects also favor attack at the less hindered SiMe2 end of the disilene, thus leading to 26. 

Under palladium(n) catalysis 2-alkynylbenzyl alcohols 136 can cyclize by either a 5-exo-dig process to form (Z)-l-alkylidene-l,3-dihydrobenzofurans 138 or a 6-endo-digprocess to afford 177-isochromenes 137 (Equation 66). Lower solvent polarity and alkyl, rather than aryl substitution of the alkyne favour a 6-endo-dig cyclization (Table 3) <2003T6251>. 

Table 2 Reaction of an orf/m-substituted aryl iodide with an allylic alcohol in the presence of K2C03, Pd(OAc)2 and norbomenc.1...

In contrast, the HRP-catalyzed kinetic resolution of racemic secondary hydroperoxides in the presence of guaiacol afford the hydroperoxides and their alcohols in high enantiomeric excesses (Eq. 3) [69]. In the case of the aryl alkyl-substituted hydroperoxides and cyclic derivatives (Table 4, entries 1 -3,6-10), HRP preferentially accepts the (R)-enantiomers as substrates with concurrent formation of the (R)-alcohols the (S)-hydroperoxides are left behind, further-... 

Tertiary benzylic nitriles are useful synthetic intermediates, and have been used for the preparation of amidines, lactones, primary amines, pyridines, aldehydes, carboxylic acids, and esters. The general synthetic pathway to this class of compounds relies on the displacement of an activated benzylic alcohol or benzylic halide with a cyanide source followed by double alkylation under basic conditions. For instance, 2-(2-methoxyphenyl)-2-methylpropionitrile has been prepared by methylation of (2-methoxyphenyl)acetonitrile using sodium amide and iodomethane. In the course of the preparation of a drug candidate, the submitters discovered that the nucleophilic aromatic substitution of aryl fluorides with the anion of a secondary nitrile is an effective method for the preparation of these compounds. The reaction was studied using isobutyronitrile and 2-fluoroanisole. The submitters first showed that KHMDS was the superior base for the process when carried out in either THF or toluene (Table I). For example, they found that the preparation of 2-(2-methoxyphenyl)-2-methylpropionitrile could be accomplished h... 

Several fluorinated aryl ethers 134 were prepared from the reaction of the 11,12/3-oxirane 133 <1994TL2129> with substituted benzyl alcohols (Equation 13 Table 8) <1995JME4120>. 

Non-activated aryl bromides (but not fluorides) can be used as substrates for palla-dium(0)-catalyzed aromatic nucleophilic substitutions with aliphatic or aromatic amines. These reactions require sodium alcoholates or cesium carbonate as a base, and sterically demanding phosphines as ligands. Moreover, high reaction temperatures are often necessary to achieve complete conversion (Entries 7 and 8, Table 10.4 Experimental Procedure 10.1). Unfortunately, the choice of substituents on the amine... 

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