Ring-opened product

Nucleophilic Reactions. The strong electronegativity of fluorine results in the facile reaction of perfluoroepoxides with nucleophiles. These reactions comprise the majority of the reported reactions of this class of compounds. Nucleophilic attack on the epoxide ring takes place at the more highly substituted carbon atom to give ring-opened products. Fluorinated alkoxides are intermediates in these reactions and are in equiUbrium with fluoride ion and a perfluorocarbonyl compound. The process is illustrated by the reaction of methanol and HFPO to form methyl 2,3,3,3-tetrafluoro-2-methoxypropanoate (eq. 4). 

Benzoxazole dyes exhibit irreversible degradations that involve opening of the oxazole (66). Oxacarbocyanines, eg, 3,3 -dimethyloxacarbocyariine iodide [48198-86-3] (42), react most readily with aqueous acid, whereas benzoxazole merocarbocyanines (43) react with sulfite or hydroxide ion to produce ring-opened products such as (44). 

Treatment of benzo derivatives with oxidizing agents leads to less predictable results. Thus, substituted 2,1-benzisoxazoles with nitrous acid or with CrOs/AcOH generated a variety of ring-opened products of higher oxidation state, the ratio of which depended on the amount of oxidant. These reactions are illustrated in Scheme 30. 

S-Substituted thiiranium ions react with secondary amines to give ring-opened products. Nitriles also react with thiiranium ions, probably via an open carbenium ion whose formation is favored by increasing the polarity of the medium by the addition of lithium perchlorate (Scheme 79) (79ACR282). An intramolecular displacement by an amide nitrogen atom on an intermediate thiiranium ion has been invoked (80JA1954). 

The cleavage reaction occurs in three steps O protonation of the epoxide, Sn2 nucleophilic attack on the protonated epoxide, and deprotonation of the ring-opened product. Draw the complete mechanism. How many intermediates are there Which step determines diol stereochemistry ... 

H)-diones although the latter appears less probable. Additional factors, such as the cyclization of the first-formed ring-opened products with a 5-ethoxycarbonyl group are often important. ... 

With monoamines, the oxazolones give the normal ring-opened products, A-TFA amino acid amides, but with aniline both forms... 

Oxidation of the dithiete 175 with MCPBA (1 equiv.) yielded the dithiete 1-oxide 202 which, when heated in refluxing toluene, formed a mixture of the ring-opened product sulflne 203 (blue, A ax 576 nm) and 202 in the ratio 7 1 (95TL8583). Further oxidation of 202 or oxidation of 175 with... 

Dibenzotellurophene, [RhCp Cl2]2, and silver inflate yield the ri (Te) coordinated product 329 [97JCS(D) 1579]. In the absence of silver triflate, species 330 is formed. Reduction of 329 with dicyclopentadienyl cobalt results in 331. If, however, this process is conducted in the presence of Fe3(CO)i2, ring-opened products 332 and 333 are isolated. 

The irradiation of 2-trimethylsilylfuran (29) gave the corresponding ring-opening product 30 in 68% yield (Scheme 12) (83JA6316). Other trimethylsilyl derivatives showed the same behavior (Scheme 12). The allene 32, obtained starting from the furan 31, can be thermally converted into 2,4-ditrimethylsilylfuran (33). 

Ring-opening products were observed in the photoisomerization of l-methyl-4-phenylpyrazole (73) (95JOC8138 97JOC8325) and in the reaction of 1-phenylpyrazole (74) (Scheme 27) (93JA7645). 

Recently, the photochemical behavior of 4-phenylisothiazole has been reanalyzed (98JOC5592). This compound, on irradiation in ether, gave ring-opening products and 4-phenylthiazole (3% yield) (Scheme 40). The irradiation in methanol... 

It was clearly shown by NMR spectroscopy that the addition of ammonia or primary or secondary alkylamines at position 5 of the 1,2,4-triazine 4-oxides to give the adducts 89 is a kinetically controlled process, while addition at position 3 to form the ring-opening products 85 is a thermodynamically controlled process. 

Hydrolysis and subsequent oxidation of 2-methyl-4,6,7,l Ifi-tetra-hydro[l,3]oxazino[2,3-n]isoquinoline-4-one (42) afforded ring opened product 43 (99TL8269). 

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