Halo amides

In this paper Speziale and Smith 109) described experiments which led them to modify the mechanism proposed earlier 108) for the reaction of trivalent phosphorus compounds with haloamides. The first step is considered to be attack of the trivalent phosphorus compound on a chlorine atom of the halo amide (132) to produce a resonance-stabilized enolate ion (133). This is reasonable since under conditions where the trichloroamide... 

More recently, the same group has used a simpler and more easily prepared chiral ammonium phase-transfer catalyst 99 derived from BINOL in asymmetric Darzens reactions with a-halo amides 97 to generate glycidic tertiary amides 98 (Table 1.13). Unfortunately the selectivities were only moderate to low [48]. As mentioned in Section 1.2.3.1, tertiary amides can be converted to ketones. 

HI, or Cdl2 iodofluorination with mixtures of AgF and U and mixtures of N-bromo amides in anhydrous HF give bromofluorination. Bromo-, iodo-, and chlorofluorination have also been achieved by treatment of the substrate with a solution of Br2,12, or an N-halo amide in polyhydrogen fluoride-pyridine while... 

The groups R2N and Cl can be added directly to alkenes, allenes, conjugated dienes, and alkynes, by treatment with dialkyl-V-chloroamines and acids. " These are free-radical additions, with initial attack by the R2NH- radical ion. " N-Halo amides (RCONHX) add RCONH and X to double bonds under the influence of UV light or chromous chloride. " Amines add to allenes in the presence of a palladium catalyst. ... 

The first step is an example of 12-52 and intermediate N-halo amides (69) have been isolated. In the second step, 69 lose a proton to the base. Compound 69 are acidic because of the presence of two electron-withdrawing groups (acyl and halo) on the nitrogen. It is possible that the third step is actually two steps loss of bromide to... 

Reaction between a-hydroxy or a-halo amides and NaOBr... 

Reaction between aldehydes or ketones, zinc, and halo amides... 

These conditions can also be applied to enolates prepared from a-halo amides. 

Catalysis (initiation) by a free radical, on the other hand, is fairly conclusive evidence of a radical reaction, provided it is known that the catalyst is indeed a free radical and that it does not have pronounced polar properties as well. Many classes of compound once thought to decompose exclusively into ions or exclusively into radicals are now known to do both. Peroxides are one well-known example, AT-halo-amides are another. Catalysis by benzoyl peroxide probably does indicate a radical reaction since there is no evidence that this particular peroxide tends to give ions even under the most favorable conditions. But many other peroxides are known to decompose into ions, or at least ion pairs, as well as into radicals. The decomposition of azo compounds can also be either radical or ionic, the dialkyl azo compounds tending to give radicals, the diazonium compounds either radicals or ions. Catalysis by a borderline example of an azo compound would therefore be dubious evidence of either kind of mechanism. The initiation of the polymerization of octyl vinyl ether by triphenylmethyl chloride in polar... 

As a class, halonitriles are the most genotoxic of the DBFs studied in mammalian cells [19], and they are third in cytotoxicity, similar to other N-DBPs, halo-amides, and halonitromethanes. 

Oxazolidinediones can be obtained from electrochemical reduction of a-halo amides in the presence of carbon dioxide. Originally, the 2,4-oxazolidine-... 

Kang and co-workers prepared the (3-halo amide arrangement required for oxazoline formation from allylic alcohols via a two-step process. For example, treatment of the allylic alcohol 122 with trichloroacetonitrile and base followed by activation of the double bond with iodine monochloride, provides 123. Hydrolysis of 123 gave 124 from which cyclization provided the oxazoline 18a used for paclitaxel synthesis (Scheme 8.36). 

Alkyl hypochlorites and N-halo amides add to isocyanides to give, after hydrolysis, carbamates and N-acylureas (ureides), respectively.806... 

A similar reaction has been carried out on N-halo amides, which give y-lactones 612... 

Barton Beckwith Goosen/. Chem. Soc. 1965, 181 Petterson Wambsgans/. Am. Chem. Soc. 1964,86, 1648 Neale Marcus Schepers J. Am. Chem. Soc. 1966,88, 3051. For a review of N-halo amide rearrangements, see Neale Synthesis 1971, 1-15. 

Reaction between aldehydes or ketones, zinc, and halo amides 6-41 Reaction of aldehydes with the conjugate base of formamide reaction of ketones with imines 6-67 Reaction between isocyanides, TiCI4 and aldehydes or ketones, followed by hydrolysis... 

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