Ring double, carbonylative

Particularly alkyl halides which have a perfluoroalkyl group at the /3-position undergo smooth carbonylation. Probably the coordination of fluorine to form a five-membered chelate ring accelerates the reaction. Double carbonylation to give the a-keto amide 915 is possible in Et NH with the fluorine-bearing alkyl iodide 914[769,770]. The ester 917 is obtained by the carbonylation of the /3-perfluoroalkyl iodide 916 in ethanol. 

The spectra fit the ester structure well, but not the more symmetrical diketone structure at all. There are three types of proton (cyclobuta-l,3-dione would have just one) with allylic coupling between one of the protons on the double bond and the CH2 group in the ring. The carbonyl group has the shift (185 p.p.m.) of an acid derivative (not that of a ketone which would be about 200 p.p.m.) and all four carbons are different. 

Strategy Both sets of reactants cleave double bonds. Aqueous KMn04 produces a carboxylic acid from a double bond carbon that is monosubstituted and a ketone from a double bond carbon that is disubstituted. Ozone produces an aldehyde from a double bond carbon that is monosubstituted and a ketone from a double bond carbon that is disubstituted. If the double bond is part of a ring, both carbonyl groups occur in the same product molecule. 

Mercuric bromide, HgBrj (mp 236 °C), oxidizes methylene groups that are adjacent to double bonds or aromatic rings to carbonyls [11]. 

On exposure to UY irradiation the reactions of quinones involve their carbonyl groups and the ring double bonds. Quinones arecapable of abstracting hydrogen atoms from various hydrogen donors. The singlet and triplet states of quinones are considered to be the initial reactive inter mediate in the reaction ... 

The irradiation of the ionones (227) at A > 254 nm at room temperature affords the three ethers (228), (229), and (230). The products (228) and (229) are the result of oxetan formation by way of the two possible addition modes of the carbonyl group to the ring double bond. The other product (230) arises from the biradical (231), again an oxetan forming mode, but hydrogen... 

Just as in the case of the pyrimidines, OH-radical attack is by addition to a ring double bond targeting a carbon atom (but not the guanine carbonyl carbon), to the practical exclusion of H-atom abstraction reactions. However in the purines, the relative importance of the target sites is more difficult to assess for two reasons. First, the five (adenine) or four (guanine) OH-adducts that are formed in reactions (64)-(72) do not show a pronounced difference in their redox behaviour as the two (for each) pyrimidine-derived ones do. 

C. See if any of the carbon atoms shown in the spectrum are part of recognisable groups, such as carbonyl groups, aromatic rings, double bonds, nitrile groups, etc. 

The proposed mechanism, which is based on the double carbonylation of styrene oxide, is shown in Scheme 6.2. The generation of an acylcobalt carbonyl complex from the reaction of cobalt tetracarbonyl anion with an alkyl halide is followed by reaction with a thiirane. This species can undergo carbonylation, the thioester function can undergo hydrolysis to reveal a sulfido nucleophile, and intramolecular cydization then produces thietan-2-one. The thietan-2-one can undergo ring cleavage and the mercapto acid results by protonahon. 

The use of secondary amides as nucleophiles has been also documented by Mori et al.f Synthesis of imides by this method is not always satisfactory, but phthalimides are prepared in high yield (Scheme 44). An interesting modification of this method consists of the double carbonylation of o-aryl diiodides and proceeds via an initial intermole-cular amidation, followed by the intramolecular one described by Mori (Scheme 45). ° The formation of seven-membered rings was demonstrated by the synthesis of diazepam and a number of anthramycin alkaloids, including Prothracarcin and Tomaymycin (Scheme 46). As mentioned above, for seven-membered rings direct amination is observed as a side reaction. Secondary ureas are also substrates for this reaction, yielding seven-membered cyclic ureas. ... 

Ring Closure Reactions Kedhkar et al. studied the synthesis of phthalimides 41 by double carbonyl-ation of o-dihaloarenes, o-halobenzoates, and o-iodobenzoic acid with CO and amines catalyzed by palladium on carbon (Pd/C) in the presence of DABCO (1,4-diazabicyclo (2.2.2) octane) as base additive (Scheme 27) [116]. The... 

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