Acyl halides/epoxides

Anhydride, acyl halide. Epoxide, aziridine orthiirane... 

MetaDrug also includes 89 rules to predict likely reactive metabolites such as quinones, aromatic and hydroxyl amines, acyl glucuronides, acyl halides, epoxides, thiophenes, furans, phenoxyl radicals, phenols, and aniline radicals. Molecules with reactive groups are marked and highlighted. 

Treatment of Na2pe(CO)4 with an acyl halide produces 143 that, when treated with an alkyl halide, gives a ketone or, when treated with an epoxide, gives an ot,P-unsaturated ketone. 

Reactive structures that interfere with the biochemical assay (aldehydes, acyl-halides, sulfonyl-halides, Michael acceptors, epoxides, aziridines, oximes, N-oxides). 

Metallostannation often gives a better regio- and stereoselectivity than does hydrostannation, and the vinylmetal group that is formed can often react further with suitable electrophiles such as halogens, acids, alkyl halides, acyl halides, metal halides, aldehydes, or epoxides.110 ... 

Decarbonylation of acyl halides 7-20 Cleavage of Michael adducts 7-21 Deoxygenation of vic-diols 7-22 Cleavage of cyclic thionocarbonates 7-23 Deoxidation of epoxides 7-24 Desulfurization of episulfides 7-25 Reaction of a-halo sulfones with bases (Ramberg-Backlund)... 

Swain, C. G., and C. B. Scott, Quantitative correlation of relative rates. Comparison of hydroxide ion with other nucleophilic reagents toward alkyl halides, esters, epoxides, and acyl halides , J. Am. Chem. Soc., 75, 141-147 (1953). 

Since such reactivity has recently been reviewed,8 only a few examples are reported here. Acyl halides or epoxides can be alkynylated with preformed silver acetylides. Such processes have been applied to the total synthesis of the antibiotic macrolide (+ )-methynolide,96 and in the total synthesis of the antitumor agent FR901464 isolated from a Pseudomonas species (Scheme 10.62).97... 

The discussion above emphasizes that the allyl-Ni reagents are quite selective for carbon halogen bonds, especially allyl, vinyl, and aryl halides. At the same time, modest reactivity as nucleophiles toward reactive carbonyl derivatives has been reported.Simple aldehydes, the more reactive ketones (such as cyclopentanone and benzoquinone), and certain epoxides will undergo 1,2-addition of the aUyl ligand to the carbonyl group. Esters, amides, and, most remarkably, acyl halides are inert toward the allyl Ni reagents under conditions where the reagents do not decompose thermally (<80 °C or so). 

Other electrophiles that react with in situ-generated perfluorocarbanions in elude epoxides [226] equation 47), carbon dioxide [227] (equation 47) acyl halides [228, 229, 230, 20, 232, 233] (equation 48), fluoroformates [23d] car bonyl fluonde [23S, 236, 237] hexafluorothioacetone (generated from its dimei) [238] (equation 48), an a-fluoroalkylamine f2J9] (equation 48), cyanuric fluoride [240], and reactive alkyl halides [247, 242 243, 244, 245] (equation 49) Interestingly, an in situ-generated carbanion will also react with dibromodifluoromethane ia a mechanism involving difluorocarbene [246] (equation 50)... 

The synthesis can be extended to the preparation of ketones in six distinct ways. " These include quenching 180 with a second alkyl halide (R X) rather than acetic acid omitting PPhs with first RX and then adding the second, R X treatment with RX in the presence of CO, followed by treatment with R X treatment with an acyl halide followed by treatment with an alkyl hahde or an epoxide, gives an a,p-unsaturated ketone. The final variations involve reaction of alkyl halides or tosylates with Na2Fe(CO)4 in the presence of ethylene to give alkyl ethyl ketones when 1,4-dihalides are used, five-mem-... 

In the benzoin condensation, one molecule of aldehyde serves as an electrophile. If a carbanion is generated from protected cyanohydrins, a-aminonitriles or dithioacetals, it can react with electrophiles such as alkyl halides, strongly activated aryl halides or alkyl tosylates to form ketones. Amongst other electrophiles which are attacked by the above carbanions are heterocyclic A -oxides, carbonyl compounds, a,p-unsaturated carbonyl compounds, a,3-unsaturated nitriles, acyl halides, Mannich bases, epoxides and chlorotiimethyl derivatives of silicon, germanium and tin. 

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