Methyl bromomalonates

In contrast, when the reaction was conducted using diethyl malonate instead of bromomalonate in the presence of Na2C03 under the HSVM conditions, there was obtained not the cyclopropanated product but a C o derivative having two bis(ethoxycarbonyl)methyl groups at the 1,4-positions 46 in 18% yield (82% based on consumed Cgo) (Scheme 21) [52]. Previously it was reported that... 

With Mn(OAc)3, generated by oxidation of Mn(OAc)2 as mediator, a tandem reaction consisting of an intermolecular radical addition followed by an intramolecular electrophilic aromatic substitution can be accomplished [Eq. (21b)] [225b]. Further Mn(III)-mediated additions of 1,3-dicarbonyl compound to olefins are shown in Table 11 (numbers 8b,c, and 9a). Mediated by in situ generated Mn(III), methyl dibromoacetate, trichloro-bromomethane, perfluoroctyl iodide, dimethyl bromomalonate, and active methylene compounds have been added via radicals to olefins [225d]. 

Compound 16 has been syntheased [52] as described in the Scheme T. Methyl-amino benzoate 16a reacts with diethyl bromomalonate to give 16b, which has been acylated with 3-bromo propionic acid and PCI3 to provide 16c. 

Ethyl 2-bromoacetoacetate reacts with triethyl phosphite to give a mixture of diethyl l-(ethox-ycarbonyl)-2-oxopropylphosphonate (29%, Michaelis-Arbuzov product) aud diethyl l-methyl-2-(ethoxycarbonyl)vinyl phosphate (31%, Perkow product). By contrast, the reaction of diethyl bromomalonate with trialkyl phosphites takes only one course, and the products formed at either temperature are the enol phosphates (Perkow product) ... 

The issue of 1,2- versus 1,4-addition, as shown in Scheme 22, in the phase transfer catalyzed (benzyl-triethylammonium chloride TEBA) version of this cyclopropanation reaction, was addressed in a more recent publication. Simple a-halo esters do not react with acrolein, methyl vinyl ketone or 2-chloroac-rylonitrile under the conditions examined. However several electrophilic alkenes do react with diethyl bromomalonate to give good yields of substituted cyclopropanes (equation 38 Table 13). The only side... 

Introduction of arylsulfonylmethyl substituents into nitroheteroaromatic rings is of great practical value because these sulfones are versatile intermediates in organic synthesis. Nitrobenzyl aryl sulfones and their heterocyclic analogues can easily be transformed into the corresponding ethenyl derivatives by a simple alkylation with simultaneous elimination of arylsulfinate anion [125]. Diethyl methylenemalonate substituent can be introduced in the positimi 4- of 5-nitroimidazole via the VNS reaction of 5-nitroimidazole with the carbanion of chloromethyl phenyl sulfone [112, 124], followed by condensation of the obtained 4-(phenylsulfonyl)methyl derivative with diethyl bromomalonate or diethyl ketomalonate (Scheme 33) [126]. 

A range of aromatic and heteroaromatic nitroalkenes reacted smoothly with ethyl as well as methyl hromomalonates to give the corresponding cyclopropanes in high yields and enantioselectivities (85-99% ee). To explain the stereoselectivity of the process, the authors have proposed that the bromo-malonate was activated by the nickel catalyst through a bidentate fashion. Then, the bromomalonate anion attacked the Si face of the double bond of the nitroalkene, as shown in the transition state depicted in Scheme 2.43. 

A French group have described the low-temperature dealkoxycarbonyla-tion of jS-ketoesters by boric anhydride, B2O3. A further example of thermal demethoxycarbonylation of substituted malonate esters has been reported halogen participation in charge dispersal has been invoked to account for the production of methyl bromoacetate from dimethyl bromomalonate (Scheme 26). 

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