Lactones ethylene derivatives

Manganese triacetate y-Lactones from ethylene derivs. 

A short synthesis of ( )-isostegane, a tetracyclic dibenzocycloota-diene lactone, has been achieved by a sequential double a, -substitution of an electron-deficient ethylene derivative, in this case zl P-butenolide, followed by non-phenolic oxidative coupling with VOFg . An equally short synthesis of methyl jasmonate has been achieved through 1,4-addition-alkylation of cyclopentenone . 

Chloronitrones are enophiles which undergo cycloaddition with non-activated ethylene derivatives. The latter can thus be used for the preparation of 7-lactones or the extension of the C-chain at one end of the double bond, which is cleaved in the process . ... 

Via intermediates Synthesis of ethylene derivs. from enamines via thioenolethers a,y - thylene-y-lactone side-chain synthesis... 

Problem 64.—/i-Lactones are usually unstable and break down to yield carbon dioxide and an ethylene derivative Write the equation for such a reaction. 

Dialkoxycarbonylation has been reported using a Pd-catalyst/oxidant system on propynols or butynols furnishing respectively /3- or y-lactone derivatives with a-(alkoxycarbonyl)ethylene chains (Scheme 24) [83,137, 138]. This reaction occurs in a stereospecific way leading exclusively to cis-dicarbonylated products in fair to excellent yields (25-97%). Noteworthy, a butynol bearing an alkyl or an aryl substituent instead of a TMS one undergoes a different course of reaction under the same conditions here frans-alkoxycarbonylation takes place selectively (Scheme 25). 

Varela et al. have described some stereoregular hydroxylated polymannaramides (91) [93] by reaction of o-mannaro-l,4 6,3-dilactone (90) with even-numbered alkylenediamines (n = 2, 6, 8, 10, 12). Hydroxylated stereoregular and nonstereoregular polyamides were also prepared by the same authors [94] from hexam-ethylene diamine and pentachlorophenyl (25)-5-oxo-2-tetrahydrofurancarboxylate 93, the latter being derived [95] from the chiral (25)-2-hydroxypentanedioic acid 5,2-lactone (92), a compound obtained [96] by deamination of the easily available L-glutamic acid. 

Based on these reactivities various derivatives of carbenes, such as the aminocarbene 238, are prepared by displacement of the OR group in 237 with amine via addition elimination, analogous to transesterification [74,75], As an example the carbanion 240, generated by deprotonation of 239, attacks ethylene oxide to give the lactone equivalent 241, which is further alkylated by chloromethyl methyl ether, again at the -position. Finally the oc-methylene-y-lactone 242 is obtained by oxidative demetallation with a Ce(TV) salt [76],... 

The ability to accept electrons from donors is particularly pronounced in acrylic acid derivatives [85] its alkyl esters [78, 87, 88], acrylonitrile [88], acrylamide, hydroxylacrylates [85], and further in styrenes substituted with an electronegative atom or group m-nitrostyrene, 2,6-dichlorostyrene [86], / -nitrostyrene [89] bicyclobutane-1-carbonitrile [89] lactones /J-propio-Iactone [85], sulfolactone vinyl ketones [87] unsaturated dicarboxylic acids and their derivatives diethyl fumarate, fumaronitrile [90], ROOC—N— N—COOR [86], cyclic anhydrides of diacids [91 ], particularly maleic anhydride [78, 92] ethylenes substituted with electronegative groups [93, 95]... 

Cleavage of lactones and carbonates. Lactones and carbonates react with bromotrimethylsilane to afford bromocarboxylic acid derivatives (equation I) and bromohydrin trimethylsilyl ethers (equation II), respectively acyclic, aliphatic esters do not react with bromotrimethylsilane. lodotrimethylsilane reacts in an analogous fashion with lactones, but in reaction with ethylene carbonate the main product is 1,2-diiodoethane (equation III). The >-bromocarboxylate derivatives are converted into acid chlorides by reaction with SOCL (equation I). 

In the field of olefin carboxylation, stoichiometric reactions have been described to occur between non-activated alkenes, CO2 and an electron-rich transition-metal complexes, such as Ni(0) [3], Ti(II) [4] or Fe(0) [5]. A Pd-catalyzed CO2 fixation occurs into methylenecyclopropane derivatives affording lactones [6]. The reaction of carbon dioxide with ethylene is difficult and its carboxylation to propionic acid, catalyzed by Rh derivatives [7], needs drastic experimental conditions. 

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