Synthesis of α-halomethyl ketones: Oxidative hydrolysis of vinyl halides

Highly Efficient Synthesis of New α‐Arylamino‐α′‐chloropropan‐2‐ones via Oxidative Hydrolysis of Vinyl Chlorides Promoted by Calcium Hypochlorite

“…Only the simultaneous presence of a deactivating group [chloro 14a, or nitro (12a and 16a)] on the aromatic ring assures that reactions afford cleanly the desired ketones (18)(19)(20) without any aromatic chlorination; in fact, the unsubstituted methyl amide 13a, under the same reactions conditions yielded 19, in which we observed not only the desired oxidative transformation of the vinyl chloride, but also a con-comitant insertion of a chlorine atom at the para position of the phenyl ring. The same compound 19 was obtained starting from acetamide 14a, in which a chlorine atom is already at the para position.…”

“…In previous works [19,20] it was emphasised the presence of a protic acid (HX or AcOH), is a conditio sine qua non to generate the a-halo ketone. However, no explanation has been proposed yet.…”

“…On the other hand, Weinreb et al, [19] based on earlier observations by Morton and Leanna, [20] verified a new one-step conversion of vinyl halides to a-halo ketones by treatment with a hypohalite in acidic media. Thus, if this transformation could be extended to Naryl-containing vinyl chlorides, it could lead to the preparation of a-arylamino-a'-chloro ketones.…”

New reactions in water: metal-free conversion of alcohols and ketones into α-iodoketones

“…5 To overcome intrinsic limitations associated with the iodination reaction of ketones the use of related masked forms, such as the corresponding enols, became popular from an early stage. Their reactions towards several iodinating agents and conditions were studied 6 and often utilized, even at the expense of a lengthy overall sequence. Furthermore, the consideration of iodide as the iodine source has been scarcely investigated, 7 and is routinely associated with those iodination processes based on exchange reactions of previously a-functionalized precursors.…”

Direct Conversion of Olefins into α-Bromo Ketones Using O-Iodoxybenzoic Acid and Tetraethylammonium Bromide

“…Direct oxidative transformation of olefins to a-halo ketones provides 1,2-difunctionalized synthons useful for construction of heterocyclic rings such as imidazoles, 1a oxazoles, 1b thiazoles, 1c triazoles, 2a benzofurans, 2b 1,4benzodioxans, 2c pyrazines, 2d and others. 3 The few methods available for direct conversion of olefins to a-halo ketones include oxidative hydrolysis of vinyl bromides with aqueous N-bromosuccinimide, 4 treatment of enol ethers and acetates with lead(IV) acetate in the presence of metal halides, 5 treatment of olefins with sodium bromite in acetic acid, 6 and vanadium-catalyzed bromination of olefins. 7 Recently, two new methods have emerged using hypervalent iodine(V) reagent IBX in combination with NBS or NIS 8 and iodine.…”