Electron-Deficient Aromatic Systems

It appears that in the presence of electron-rich 7T-systems, either olefinic or aromatic, these electron-deficient diacyl peroxides undergo electron-transfer, decarboxyation, and cage-recombination to give adducts in good yield [68]. 

Electron-Deficient Polymers - Luminescent Transport Layers 16 Other Electron-Deficient PPV Derivatives 19 Electron-Deficient Aromatic Systems 19 Full Color Displays - The Search for Blue Emitters 21 Isolated Chromophores - Towards Blue Emission 21 Comb Polymers with Chromophores on the Side-Chain 22 Chiral PPV - Polarized Emission 23 Poly(thienylene vinylene)s —... 

As in molecular chemistry, an alternative path to compensate for electron deficiency is the formation of multiple bonds, through 7r-interactions, as in unsaturated and aromatic molecular systems. Our work in Houston focuses on probing the efficacy of the ZintI concept in rationaUzing stoichiometries, crystal structures and chemical bonding of complex electron-poof ZintI phases that exhibit novel i-systems. Their chemical bonding is reflected by their unusual crystal structures related to unsaturated hydrocarbons [53]. 

Recently, Kraft and Osterod [157] reported the synthesis of poly(aramide) dendrimers possessing either electron-deficient 1,3,4-oxadiazole (70) or aromatic systems (71) linked by amide units to a central triphenylmethane unit (Fig. 31). 

Dendrimers, which contain an electron-deficient 1,3,4-oxadiazole ring and aromatic systems linked by amide units to triphenylmethane core, were synthesized (Scheme 16) <1997CC1435>. 

Friedel-Crafts Alkylations and Mukaiyama-Michael Reactions The metal-catalyzed addition of aromatic substrates to electron-deficient a- and 7i-systems, commonly known as Friedel-Crafts alkylation, has long been established as a powerful strategy for C-C bond formation. Surprisingly, however, relatively... 

This work has been extended from aryl and alkyl substituted systems (42) (R = aryl, alkyl) to analogues where R is an amino group, so giving access to synthetic equivalents of the nonstabilized amino nitrile ylides (45). Adducts were obtained in good-to-moderate yield with A-methyhnaleimide (NMMA), DMAD, electron-deficient alkenes and aromatic aldehydes (27,28), and with sulfonylimines and diethyl azodicarboxylate (29). Similarly the A-[(trimethylsilyl)methyl]-thiocarbamates (46) undergo selective S-methylation with methyl triflate and subsequent fluorodesilylation in a one-pot process at room temperature to generate the azomethine ylides 47. 

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