Perbenzoic acids hydroxylation with

Perbenzoic acid gave a doubly unsaturated triol monobenzoate. Only two hydroxyl groups could be acetylated, and one was tertiary. The saturated triol reacted with lead tetracetate to give an a glycol. When reacted with chromic acid, it gave a hydroxy lactone. From these observations, Windaus and Gmndmann (11) described the correct stmcture for ergosterol (1). 

In hydroxylation, quinones are usually obtained since the initial hydroxyl product is further oxidised. Kinetic studies on the hydroxylation of 1,3,5-tri-methoxybenzene with perbenzoic acid gave second-order rate coefficients (Table 29) which remained fairly constant for a wide variation in concentration of aromatic and acid thus indicating that the rate-determining step is bimolecular133. The variation was considered to be within the rather large experimental error for the reaction which was very fast and, therefore, studied at low temperature (—12.4 °C). Since more than one mole of acid per mole of aromatic was eventually consumed, the mechanism was formulated as... 

II, 20-dione, which is reacted with methylmagnesium bromide in the presence of lithium bromide to give 3a-hydroxy-16a-methylpregnan-ll,20-dione (27.1.39), after which a Ha-hydroxyl group is added. This is done by a reaction with acetic anhydride in the presence of p-toluenesulfonic acid, forming the 3-acetoxy-17-enolacetate 27.1.40, which is epoxidized by perbenzoic acid 27.1.41, and the product is hydrolyzed by an alkali to give an oxyketone... 

Hydroxylation Perbenzoic acid (C6H6, 100°) can effect hydroxylation of hydrocarbons with a regioselectivity of 60-90% in favor of formation of tertiary alcohols. This reaction involves radicals since it is inhibited by hydroquinone. The hydroxylation of cis-and trans-decalin is stereoselective thus the former is converted mainly into cw-9-decalol (97 3) and the latter is converted mainly trans-9-decalol (95 5). 

W. Muller and H.-J. Schneider, Regio- and stereospecific hydroxylation of allylic hydrocarbons with substituted perbenzoic acids, Angew. Chem. Int. Ed. Engl., 18 (1979) 407-408. 

Method of hydroxylation (c) = cis, with neutral permanganate (t) = trans, with perbenzoic acid. 

A particularly important reaction of D-glucal is that with perbenzoic acid. The products formed in the reaction have hydroxyl groups attached to carbon atoms 1 and 2, which represents a return to aldoses. As an intermediate product the 1,2-epoxy ring is assumed, which is secondarily cleaved by water or other hydroxyl-containing substances.8 By this reaction, both carbon atoms 1 and 2 become asymmetric again... 

Epimerization of the Aldoses.—When the glycals are treated with perbenzoic acid, oxygen adds to the double bond and the epoxide reacts with water to yield a mixture of epimeric aldoses. Usually one aldose predominates. When the hydroxyl at carbon atom 3 is substituted, a... 

A 1,2-diol arising from a trans-hydroxylation process is formed from an alkene by way of an intermediate epoxide which is subjected to a ring-opening reaction and hydrolysis. The epoxides may be isolated when the alkene is reacted with perbenzoic acid or m-chloroperbenzoic acid (Section 4.2.56, p. 457) in a solvent such as chloroform or dichloromethane the preparation of epoxides by this method and by other important procedures are discussed and illustrated... 

Further substantiation for this interpretation was obtained by Micheel by characterization of the hexomethylose (XXXIX) formed when digitoxal is oxidized with perbenzoic acid. The phenylosazone of XXXIX showed the same melting point as that of L-altromethylose and the rotation was of equal value but of opposite sign. The product of the perbenzoic acid oxidation of digitoxal possesses the configuration demanded by the theory later advanced by Levene and Tipson in the case where the C-3 hydroxyl group is unsubstituted. 

With perbenzoic acid gives a mixture of about equal amounts of the cis- and froRf-epoxide. If the hydroxyl group is first silylated, then oxidation with m-Ohloroperbenzoic acid gives the trans-epoxy ether as the main product. ... 

Many mechanisms have been proposed for this reaction, such as the epoxidation via initial attack of a hydroxyl cation, 1,3-Dipolar Cycloaddition of a hydroxycarbonyl oxide to an olefinic double bond, and the commonly accepted planar butterfly transition state, " by which the n HOMO orbital of the olefin approaches the terminal oxygen of perbenzoic acid and interacts with the a LUMO of the 0-0 bond at 180". The planar butterfly transition state is further extended by Sharpless to a spiro-trunsition state, which has been consolidated by many other investigators. An illustrative mechanism from mCPBA epoxidation is provided here. 

Hydroxylation of the double bond of 1,2-D-glucoseen tetraacetate is accomplished either with perbenzoic acid 126) or, indirectly, through the addition of chlorine and its replacement with hydroxyl provided by moist... 

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