Lateral cyano groups

The polyarylesterketone eopolymers, containing lateral cyano-groups, can be s mthesized [390] on the basis of bisphenyl oxide, 2,6-bisphenoxy-benzonitrile (I) and terephthaloylchloride in the presence of AICI3, employing 1,2-dichloroethane as the dissolvent, N-mthyl-2-pyrrolidon as the Lewis base. With increasing concentration of links of I the crystallinity... 

ZLl 1253 and ZLl 1285 (see Ref. 36)). The enhanced liquid crystal behavior of the three ring ester system is shown by the fact that negative nematic materials are possible with a lateral cyano group (Licristal S1014, Ref. 36). An extrapolated Ae of -4 at room temperature is one of the highest known (31e). 

Low rotational viscosities, which are necessary for outdoor or video applications of liquid crystal displays, are obtained in mixtures with unpolar substances having short side chains such as, for example, dialkylcy-clohexylphenyls or the corresponding alkenyl compounds [83, 84]. Lateral substitUT ents lead to a viscosity increase as well as the substitution of hydrogen atoms at the benzene ring by halogens. The effect is small for fluorine atoms and increases in the sequence F[Pg.1144]

We have also synthesized a number of similar copolymers and model compounds bearing cyano groups on the vinylene linkages (Section 16.2.1.3.4). The nomenclature of the models referred to later in this chapter is given in Figure 16-5. 

However, experiments which may be considered as simplified models of the degradation were not carried out until some years later. In 1897, Colson, working with the acetates of lactic nitrile and a-hydroxybutyric nitrile, showed that treatment with silver acetate removed the cyano groups and that acetic acid and acetaldehyde or propionaldehyde were produced. 

The present preparation employs a method of considerable scope which gives much better yields and is considerably less laborious than other methods for the preparation of tert-butyl cyanoacetate. The compound is of specific interest since, for example, it may be used in any reaction where ethyl cyanoacetate is used (condensation reactions, etc.), but it has the added advantage that the carbo-feri-butoxy group, which may serve in conjunction with the a-cyano group to activate the a-hydrogens (for cyanoethylations, etc.), may be later removed simply by pyrolysis of the compound. 

Other cyano complexes of Fem, containing only one or two cyano groups, will be considered in later sections which focus principally on the coordination chemistry of the associated ligands. 

Other type III peptidomimetic inhibitors of this enzyme have also been reported. Inhibitor (112) (Fig. 15.47) was developed by replacing the A1A2 dipeptidyl sequence with a benzodiazepine scaffold (209). Later, SAR modifications of the benzodiazepine nucleus that included a hydrophilic 7-cyano group and a 4-sulfonyl group provided the potent, orally available and in vivo active (113) (210). 

Oxymercuration of cyanohydrin 98 was examined as a third option (Scheme 21) [52]. Treatment of this cyanohydrin under Hg(II) trifluoroacetate-mediated brominative conditions afforded tetra-hydropyran 99. Inversion of configuration at C3 by allowing 99 to react with Br2 under photolytic conditions afforded pyran 100. DIBAL-H reduction of the cyano group provided aldehyde 86 in racemic form. This method was later abandoned due to the difficulties in obtaining or synthesizing an enantiomerically pure starting material (98). 

Termite soldiers produce a large number of different chemical defense agents. Several of these molecules are unusual bioactive terpenoids such as the secotrinervitanes that have been isolated and their structure elucidated. In the laboratory of T. Kato, the total synthesis of (+)-3a-acetoxy-7,16-secotrinervita-7,11-dien-15P-ol was accomplished. The Nagata hydrocyanation was used to introduce a carbon at the P-position of a macrocyclic enone intermediate. The substrate was treated with excess diethylaluminum cyanide in dry toluene and the addition resulted in the formation of a 1 1 mixture of diastereomers, which could be readily separated by column chromatography. The cyano group was later converted to the corresponding methyl ester. 

Carboxylic Acid Derivatives generally have a acyl group(RC=O) attached to an electronegative atom, with the notable exception of nitriles (Alkyl group attached to a cyano group). Illustrated examples should be added at some later time. Please see John McMurry s Organic Chemistry 6th edition chapter 22 for further explanation on this topic... 

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