Synthesis of α-hydroxy ketones ..
hydroxy ketones in good yields by potassium permanganate oxidation
The ketone enolate forms easier than the ester enolate since their a-hydrogens are more acidic. Thus, the ketone will act as the nucleophile and the ester will behave as the electrophile.
Hydroxy ketone synthesis by oxidation - Organic …
Esters must have at least two a-hydrogen atoms to undergo the Claisen condensation; one hydrogen is removed to form the enolate, a second hydrogen is removed from the b-ketoester. The second proton abstraction is the driving force step.
Alpha-hydroxy ketone - WikiVisually
However, there are many exceptions to this sequence depending on the reagents used, as well as steric and electronic effects in the substrate. In addition to peracids, alkaline hydrogen peroxide or hydrogen peroxide together with a Bronsted or Lewis acid like BF3 can also be effective. The migratory tendency can be quite different with different reagents. For example, benzaldehyde gives mostly H migration with KHSO5, mostly Ph migration with H2O2/NaOH, and about equal amounts of both with MCPBA. Electron rich aryl rings migrate preferentially over electron poor ones, and thus the sequence among secondary, aryl, and hydrogen migratory aptitudes can be changed by substituents on the aromatic ring. Vinyl groups migrate comparably to aryl, but the enol ester products are often epoxidized during the reaction.
Sterol synthesis : chemical synthesis of 3 beta-hydroxy-5 alpha ..
Synthetically related to the Baeyer-Villiger oxidation is the haloform reaction, inserted here for lack of a better location. In the haloform reaction methyl ketones are cleaved to carboxylic acids by treatment with 3 equiv of bromine, chlorine or iodine in the presence of base. The reaction involves consecutive α-halogenations of the methyl group to form a trihalo-ketone, which is then cleaved in a Grob-type fragmentation.