Peroxy adds

EpoxyacetateB have also keen prepared from steroid end aoetatc by Huechmann and Wendler,7 Soloway and co-workers,1801 and Leeds and eo-workers.888 Moffett and Stomp 187 have found, with certain unsatorated steroid enol acetates, that where a choice reaction sites exists perbenzoic add attacks a simple olefinie double bond preferentially. At higher temperatures and with excess l peroxy add, however, there ooouzs epoxidation of the enol acetal... 

A pertinent related example was published by King and <.< workers, 2 illustrating the formation of a tive-momhored ether inxti-.ul of a lactone (Kq. 48). A similar instance of ether-ring formation tlurin" peroxy add treatment of 2-allyIphendhae been described by Tintk- l > i and more recently by Harrison and Aelony.11 5... 

Wjtnauer and Swem1M demonetrated the remarkable stereo-specificity of peroxy add oxidation, by converting oleic acid into rit-d, 10-epoxystearic add, and elaidic acid to in i -9,LC-epoxystearic acid (Eqe. 28, 29). Julietti and co-workeis recently obtained similar (esults with the cis- and tarne-iaomers of octadeo-6-euoic add and octodeo-13-enoio add.w ... 

Silverstein and coworkers have used the peroxy add oxidation of exo-all lidene cycloalkanones as a route to keto acids (Scheme 23). Oxidation of pulegone (72) and hydrolysis of the derived enol lactone led to the keto acid 3). 

Another apedal a ect of peroxy add oxidation concerns ruputre reactions occasionally encountered when ketone groups are in... 

Several peroxy adds are used in the oonversion of olefins into epoxides. Their properties and pr tarations have been described by Swern, -Included among them are perfbrmio add, peracetic add, perbenxoio acid, monoperphthalic add, and percamphorio acid. More recently irifluoroperacetic acid hsa attained some prominence. Certain desirable features have been discovered in p-nitroperbenzoic add aa well. ... 

Witnauer and Swem " demonetrated the remarkable stereo- pecifi tty of peroxy add oxidation, by converting oleio acid into 10-epoxystearlc add, and elaidio acid to traas-d.LO-epoxystearic acid (E(. 28, 2g). Julietti and co-workers reoently obtained similar tvsults with the cU- and tmn -isomers of octadeo-6-enoic add and octadeo-13- noio add. ... 

Other olelius bearing polar atoms in the vicinity of tbe double bond that have been converted into the corresponding 1,2-dids by treatment with a peroxy add and subsequent alkaline hydro-]yei i e, 233, i27 , 1S7P are the substances shown in Eq, (751), In these instances the direction of ring fission is unfortunately not known, since 1,2-diol monoesters thereby generated were for the most part hydrolyzed directly. 

Oxidations of aromatic aldehydes to formyl esters of phenols and to phenols are accomplished by hydrogen peroxide [171, 172, 173] or by organic peroxy adds such as peroxyacetic acid [259], peroxybenzoic acid [302], and m-chloroperoxybenzoic acid [5/5, 318] (equations 360-363). 

Peroxy adds may epoxidize unsaturated ketones [299, 332], but a concomitant Baeyer-Villiger reaction is possible [254] (equations 389 and 391). Other ways of forming epoxy ketones are reactions with salts of hypochloric acid [691, 704] and with V-bromosuccinimide [746]. Mesityl oxide is converted into its epoxide, as shown in equation 437 [142, 220, 254, 746]. 

Primary aromatic amines are oxidized to nitro compounds by peroxy adds perboric acid [194], peroxysulfuric acid [203], peroxyacetic acid [253],... 

Peroxides, test for, 41, 92 Peroxy adds from carboxylic acids and 70% hydrogen peroxide, 43, 96 Peroxybenzoic Acro, 43,93 iodometric analysis of, 43, 94 Peroxystearic add, 43,96 Phenacylamine hydrochloride, 41, 82... 

The key intermediate is a peroxy-acid formed after decarboxylation. The peroxy-add is perfectly placed for an intramolecular epoxidation of a double bond in the benzene ring next to the side chain. 

Epoxides are usually prepared from olefins and peroxy acids (especially peroxybenzoic acid) according to the following general procedure The olefin is dissolved in chloroform, cooled, and treated with a slight excess of peroxy add in cold chloroform. The reaction mixture is set aside at 0°, or for less reactive olefins at room temperature. The course of the reaction is followed by titration of small samples when the reaction is ended, unchanged peroxy acid and the carboxylic acid formed are carefully extracted, and the chloroform solution is worked up. 

Perhydrohistrionicotoxin, 75, 611 Perhydrophenanthrene-9-one, 535 Periodates, 454 Periodic acid, 124 Peropyrene, 499 Peroxy adds, 260 Peroxybenzimidio acid, 455-456 Peroxycyclohexanecarboylic acid, 260 Persulfoxides, 241 Peterson reaction, 631, 636 Pfitzner-Moffatt oxidation, 227-228, 467 Phase-transfer catalysts, 10, 136, 159, 174-175, 191, 219, 249, 271, 404-406, 452, 565, 566, 586, 640-641 Phenacyldimethylsuifonium bromide, 456 Phenacyiidinedimethylsulfurane, 456 Phenanthrene, 35, 533, 669-670 9,10-Phenanthrenequinones, 47 6-477 Phenazines, 513... 

Reaction (b) is an epoxidation of an alkene, for which almost any peroxy add could be used. Peroxybenzoic acid was actually used. 

Electrophilic addition to double bonds gives three-membered ring intermediates with Bt2, with Hg2+, and with peroxy-adds (in which case the three-membered rings are stable and are called epoxides). All three classes of three-membered rings react with nucleophiles to give 1,2-difunctionalized products with control over (1) regioseledivity and (2) stereoselectivity. Protonation of a double bond gives a cation, which also traps nucleophiles, and this reaction can be used to make alkyl halides. Some of the sorts of compounds you can make by the methods of this chapter are shown below. 

The vise of per- is preferably restricted to acids derived from the highest oxidation stages of some elements e.g., HCIO4, perchloric acid) to distinguish them from acids derived from hydrogen peroxide and better called peroxy adds e.g., H2SO6, peroxy mono)sulfuric add). 

Enol ethers, and in partkiilar silylated enols (see Volume 2, ChrqMer 2.3), react with peroxy add reagents to give initially a silyloxy epoxide, which rearranges with silyl migration to yield an a-silyloxy ketone, as in Scheme 3. The net result is that a ketone is amverted to a protected a-hydroxy ketone, and die stneochemistry is determined by the least hindered approach of the peroxy acid to the enol. 

Unlike ketones, aldehydes are easily oxidized to carboxylic adds by common oxidants such as chromic add, chromium trioxide, permanganate, and peroxy adds. Aldehydes oxidize so easily that air must be excluded from their containers to avoid slow oxidation by atmospheric oxygen. Because aldehydes oxidize so easily, mild reagents such as Ag20 can oxidize them selectively in the presence of other oxidiz-able functional groups. 

For the transformation of imines to oxaziridines, in general peroxy adds (e.g., Ph-C03H) can be used. For the selective oxygenation of aryl aldimines tert-BuOOH and alumina-supported M0O3 (as a recyclable heterogeneous catalyst) are recommended... 

A reasonable mechanism is shown in Scheme 7.79. The first step is a peroxy add-catalyzed epoxidation of the alkene (491). The epoxide intermediate 496 then rapidly evolves to the corresponding diol 493 either following a S 2 mechanism (path B, Scheme 7.79), or through a S l-process via a carbocation intermediate (497, path A, Scheme 7.79), depending on the electronic and steric properties of the starting alkene. 

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