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Sulfenes, cycloaddition with imines

Thiazetidine 1,1-dioxides (-sultams) are prepared by cyclization of appropriate precursors (e.g., Scheme 20) <1975BSF(2)807> or via [Z + Z cycloaddition of imines with sulfenes 32, generated in situ from the corresponding sulfonyl chloride and an organic base (Scheme 21) . [Pg.711]

Cycloaddition of sulfenes to Schiff bases (e.g., 434) and carbodiimides yields 1,2-thiazetidine 1,1-dioxides and 3-imino derivatives. A concerted mechanism was suggested. An earlier report of the cycloaddition of a sulfene to a Schiff base lacked proof for the structure of the adduct. Best yields are obtained with two equivalents of imine. The cis isomers can be converted to trans by treatment with triethylamine. ... [Pg.594]

Alkylidene sulfenes (75), generally prepared by the dehydrohalogenation of alkylsulfonyl chlorides, add readily to electron-rich multiple bonds. For example, with enamines, the thietane dioxide (e.g., 76) is formed diazoalkanes yield thiirane dioxides (episulfones) and imines (Schiff bases) afford 1,2-thiazetidine 1,1-dioxides. There are available numerous reviews of sulfenes, including cycloaddition reactions.102... [Pg.71]

Sulfonyl chlorides possessing an a-hydrogen undergo elimination of hydrogen chloride when treated with bases to yield sulfenes. Like ketenes, sulfenes can undergo [2 + 2] cycloaddition to support-bound imines to yield p-sultams (Entry 5, Table 15.2). [Pg.392]

Acyl sulfenes, like all sulfenes, prefer to participate as 2it components of [2 + 2] or [4 + 2] cycloadditions (Chapter 5). Nonetheless, a range of [4 + 2] cycloaddition reactions of acyl sulfenes have been described46,47 (Scheme 8-XII), including their 4n- participation in dimerization reactions46-48 and reactions with imines,49 carbodiimides,50 ketenimines,51 1-azirines,52 vinyl ethers,53 and ketenes.47 The reactions often provide mixtures of [4 + 2] and [2 + 2] cycloadducts, and the observed course of the reaction usually depends on the reaction conditions. Consequently, many of the observed [4 + 2] cycloadditions of acyl sulfenes proceed by a stepwise, polar addition-cyclization reaction. [Pg.301]


See other pages where Sulfenes, cycloaddition with imines is mentioned: [Pg.554]    [Pg.267]    [Pg.752]    [Pg.378]    [Pg.267]   
See also in sourсe #XX -- [ Pg.711 ]




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Cycloaddition with

Imine 2+2] cycloaddition

Imines cycloadditions

Imines with sulfenes

Sulfenate

Sulfenates

Sulfene

Sulfenes

With imines

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