Novel conjugate reactions

A novel conjugated 7t-system consisting of a cyclopentadienide ion connected with two cyclopropenylium ions (a tripolar mesomeric system) 23 was prepared by the reaction of 1,2-diamino-3-chlorocyclopropenylium ion 22 with the cyclopentadienide or indenide ion. - ... 

The monomers (213), which were ultimately converted into novel conjugated polymers, have been prepared in poor yield by double Wittig reaction of the dialdehyde (212). Bis-Wittig reactions of l,3-propanebis(triphenylphos-phorane) (214) with ferrocenyl aldehydes (215) have been used to prepare a series of bis(ferrocenyl)polyenes (216) containing a central methylene group. These compounds were converted into the corresponding polymethine cations which are prototype molecular wires with redox-active end groups. 

A novel conjugated polymers, PI based on N, N , N , N substituted paraphenyl-enediamine and dianhydrides of aromatic tetracarboxylic acids, was successfully prepared via Suzuki coupling reaction. The polymer exhibits excellent solubility in common organic solvent, and has high thermal stability such as T j at 453°C in nitrogen atmosphere and T at about 140°C. 

FIGURE 18.10 Metabolic pathway of flavonols with quercetin nucleus (quercetin-3 -glucoside is used as an example). The heavy arrows indicate the position of conjugation. Novel metabolic reaction taken place on the aglyeone of flavonols in vivo. COMT, catechol-O-methyltransferase UGT, UDP-glucuronosyltransferase ST, sulfotransfer-ase LPH, lactase-phlorizin hydrolase CBG, C5dosolic (3-glucosidase. 

Phenylseleno)-9-borabicyclononane prepared by the reaction of 9-BBN with benzeneselenol (Eq. 32.6) undergoes a novel conjugate addition to a variety of a, (3-unsaturated ketones to alford P-selenoboron enolates, which are converted to unsaturated ketols (Eq. 32.7) on treatment with aldehydes and subsequent oxidative elimination [17]. 

Several novel conjugated 1.3-dienes, which have substituents that are able to be transformed into other functionalities, or react in the Diels-Alder reaction, have been prepared this year. An -mixture of the highly substituted 1,3-diene (41)... 

As an alternative to the classical conjugated addition reaction, Pihko and co-workers reported, in 2012, a novel CDC reaction between sp C-H bonds in the p-position of esters and indoles. Soon after, the aerobic methodology was successfully extended to a variety of electron-rich arenes and phenols... 

Lee et al. reported a novel and simple method for delivery of adriamycin using self-aggregates of deoxycholic acid modified chitosan. Deoxycholic acid was covalently conjugated to chitosan via a carbodiimide-mediated reaction generating self-aggregated chitosan nanoparticles. Adriamycin was... 

According to the Woodward-Hoffmann rule [6, 7], conjugate polyenes with 4n and 4n+2 n electrons undergo cychzations in conrotatory and disrotatory fashions under the thermal conditions, respectively. Recently, novel cycloisomerizations were found to be catalyzed by Lewis acid and to afford bicychc products [39] as photochemical reactions do [40]. The new finding supports the mechanistic spectrum of chemical reactions. 

Chan and Li reported that conjugated 1,3-butadienes were produced in moderate yields when carbonyl compounds reacted with 1,3-dichloropropene and zinc in water (Eq. 8.29).61 The use of 3-iodo-1-chloropropene instead of 1,3-dichloropropene greatly improved the yields. When the reactions were interrupted after their initial allyla-tions, subsequent base treatment of the intermediate compounds produced vinyloxiranes in high yields. Similarly, reactions of carbonyl compounds with 3-iodo-2-chloromethyl-l-propene followed by base treatment produced 2-methylenetetrahydrofurans (Eq. 8.30).62 Thus, the 3-iodo-2-chloromethyl-l-propene served as a novel trimethylene-methane equivalent.63... 

Copper hydride species, notably Stryker s reagent [Ph3PCuH]6, are capable of promoting the conjugate reduction of a,( >-unsalurated carbonyl compounds [42], Taking advantage of this trustworthy method, Chiu et al. demonstrated in 1998 an intramolecular reductive aldol reaction in the synthesis of novel terpenoid pseudolaric acids isolated from Chinese folk medicine (Scheme 28) [43]. Two equivalents of [Ph3PCuH]6 enabled cycli-zation of keto-enone 104 to provide the bicyclic diastereomers 105 (66%) and 106 (16%). The reaction also was applied to the transformation of 107... 

NLO materials (16 and 17) (Fig. 13) have been obtained from polyurethanes by the incorporation of sidechains with boron chromophores.37 The dihydroxy ligand of an azobenzene ligand containing a dimesityl boron acceptor was reacted in a polycondensation fashion with the diisocyanate groups of the polyurethanes to yield the desired polymers. Halogen displacement and transmetallation reactions have been utilized in the development of extended ir-conjugated systems of tri-9-anthrylborane with dendritic structures.38 In one (18) (Fig. 14) of the novel compounds, three identical... 

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