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Thiolactones cycloaddition

Many cycloaddition reactions have been carried out with ketenes and thioketones. The products are thiolactones (52). Hexafluorothioacetone and diphenylketene, however, do not undergo cycloaddition even after prolonged heating at 100°C. Good results can be obtained when the more stable dimer of this fluorinated thioketone (53) is used. Anionic monomer 54 could be released by the action of potassium fluoride in an aprotic solvent. Two-step cycloaddition to diphenylketene yields ketone 55. [Pg.213]

Only a limited number of examples are known of applications of thietanes in organic synthesis. Prominent among these examples would be electrophilic ring opening reactions leading to polyfunctional sulfur compounds (33)-(37), utilization of 3-thietanones (55) and metal complexes (87) derived therefrom as oxyallyl zwitterion equivalents in cycloaddition reactions, synthesis of dipeptide (63) with a /3-thiolactone, Raney nickel desulfurization of thietanes (e.g. 120 cf. Table 7) as a route to gem-dimethyl compounds, and desulfurization of thietanes (e.g. 17) in the synthesis of cyclopropanes (also see Table 7). [Pg.447]

A patent has been lodged dealing with the photochemical synthesis of the thiolactones (82) from the thioacids (83). The cycloadduct (84) is the sole product from the irradiation of 1,1-diethoxyethene with biacetyl in non-polar solvents. The authors suggest that an electron transfer process is operative and that the cycloaddition therefore proceeds via the zwitterion (85). A study of chiral induction in the photochemical synthesis of oxetanes using the chiral... [Pg.226]

Dichlorothietanes are obtained by the photochemical cycloaddition of thio-phosgene to alkenes (Section II.4.F.). Hydrolysis of the gemdichloro-methylene group yields j3-thiolactones, for example, 314.239,240a... [Pg.552]

The transition-metal-catalyzed carbonylation reaction has been extensively investigated, and especially the carbonylative ring expansion reaction of strained heterocycles has been shown to be a useful and efficient procedure to synthesize lactams, lactones, and thiolactones.203 The carbonylation of epoxides and aziridines 450 is a powerful tool to construct the /Mactone and /Mactam skeletons 451 (Scheme 142).204 This type of reactions can be regarded as a hetero-[3 + 1]-cycloaddition. [Pg.44]

The [2 + 2] cycloaddition reactions have received little attention up to 1995. The photochemically promoted addition of benzophenones to l,l-dimethyl-2,5-diphenylsilole provides the adducts (7 and (76) as the major and minor products respectively <90CC1718>. Similarly the addition of carbon disulfide to the same substrate yields the -thiolactones (77) and (78) <92TL40I3). [Pg.910]

Some examples of the [4 + 2] cycloaddition of diphenylketene to unsaturated thiones have been accomplished and reported the synthesis of the thiolactone 445 which is illustrated in Scheme 138 is common (1972JCS(P1)2326). [Pg.259]

The regioselectivity and reactivity of the 1,3-dipolar cycloaddition reactions of nitril-imines with acrylonitrile and methyl acrylate have been investigated. The 1,3-dipolar cycloaddition reactions of nitrilimines with isatin imines yielded spiro[indolin-3,3 -1,2,4-triazol] derivatives under classical and microwave conditions/ An extensive study of the 1,3-dipolar cycloaddition reactions of nitrilimines with a,/ -unsaturated lactones, thiolactones, and lactams has been presented. In all cases, regioisomeric mixtures were obtained with the 5-substituted pyrazole as the major cycloadduct. me5 o-Tetrakis(pentafluorophenyl)porphyrin (51) reacts with iminonitriles (52) yielding pyrazolin-fused chlorines (53) via a 1,3-dipolar cycloaddition reaction (Scheme 17). ... [Pg.444]


See other pages where Thiolactones cycloaddition is mentioned: [Pg.438]    [Pg.585]    [Pg.438]    [Pg.585]    [Pg.393]    [Pg.406]    [Pg.438]    [Pg.585]    [Pg.105]    [Pg.307]    [Pg.104]    [Pg.101]    [Pg.263]    [Pg.148]    [Pg.106]   
See also in sourсe #XX -- [ Pg.444 ]




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Thiolactone

Thiolactones

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