Haloamides reactions with alkenes

Furthermore, /i-haloamides 14 were obtained in low yield by reaction of nitriles with alkenes in the presence of chlorine or bromine. The tram addition led first to imino intermediate 13 which, depending on the reaction conditions, was converted into a number of heterocyclic compounds179-181. 

A general process for haloamidation of alkenes has been developed, which is characterized by the addition of a bromine atom and an amide nitrogen in an anti sense to the olefinic double bond [(7) - (8)]. The process involves the use of an A-bromoamide and a Lewis acid as a source of Br+, which reacts with the alkene. The amide group is derived from a nitrile and a water molecule, which serve as nucleophiles for the overall three-component reaction. The reaction has been shown to be general for a broad range of alkenes and nitriles an analogous chloroamidation reaction has also been demonstrated 25... 

The nitrogen source for the aziridination of alkenes, a nitrene or nitrenoid, can be generated in various ways (1) oxidation of a primary amine (2) base-induced -elimination of HX from an amine or amide with an electronegative atom X (X = halogen, O) attached to the NH group or by -elimination of metal halides from metal A-arenesulfonyl-A-haloamides (3) metal-catalyzed reaction of [A-(alkane/arenesulfonyl)imino]aryliodanes (4) thermolytic or photolytic decomposition of organyl azides and (5) thermally induced cycloreversion reactions . 

Other compounds prepared by halolactamization of alkenes (and preceding the above work ) include (64), (65), (66), 61) (68), (69) and (70). Note that related sulfeno-, seleno- and tellu-ro-cyclizations have been discussed earlier (Section 3.5.5). Finally, related products may be obtained by radical reactions of A-haloamides, giving the following (71-73) representative products in reactions promoted thermally (71),photochemically (72 and 73), ° with dibenzoyl peroxide (73) ° or chro-mous chloride (73). ... 

They can be prepared from acyclic compounds. In an industrial process, dimethyl malonate is condensed with 4-alken-3-ones (or a mixture of the respective ketones with 5-chloroalkan-3-ones) to give a substituted 3-hydroxy-2-cyclohexenone. Aro-matization, in good yield is achieved by reaction of the hydroxycyclohexenones with a suitable /V-haloamide. The intermediate 3-hydroxy-2-cyclohexenones can also be obtained by condensation of methyl 3-oxoalkanoate with methyl crotonate [182]. 

Chlorination of Alkenes and Alkynes. The haloamidation of olefins was carried out by reaction of Af-haloimides (X = Cl, Br) with nitriles in the presence of Lewis acids. It was presumed that the reaction involves nucleophilic attack of nitrile on the halonium ion followed by hydrolysis of the products (eq 38). ... 

The common methods for the S5mthesis of p-lactams are cycloaddition reactions such as the Staudinger s ketene-imine cycloadditions, ester enolate-imine cycloadditions, alkyne-nitrone cycloadditions (Kinugasa reaction), alkene-isocyanate cycloadditions, and Torii s cyclocarbonylation of allyl halides with imines. Several cyclizahon reactions of p-amino esters, p-amino acids, p-hydroxamate esters, and a-diazocarbonyls have been developed for the formation of p-lactam ring. N,N-Disubstituted a-haloamides cyclize by C3-C4 bond formation leading to the formation of P-lactam ring. 

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