Cyanophenyl derivatives

We compare the ultrafast dynamics of the l,l(8aH)-azulendicarbonitrile,2-(4-cyanophenyl) derivative (hereafter CN-DHA/CN-VHF) with the related but distinctly different DHA derivative l,2,3,8a,9-pentahydrocyclopent[a]azulene-9,9-dicarbonitril (CP-DHA). The final product formed by irradiation of CN-DHA at its Si-So absorption band around 370 nm is the CN-VHF-trans isomer. Therefore, the complete process involves a ds-trans isomerization besides the ring opening (Fig. 1). The broadband transient absorption spectra [3] reveal that an absorption band around 510 nm is formed via an excited state within the first 15 ps. This ground state absorption band is red shifted by 30 nm compared to CN-VHF-trans and can therefore be attributed to the So state of CN-VHF-cis. The rearrangement to the final trans... 

Photomodulation amperometry of the DHAs (21-24)a is shown in Figure 20. Because of the increased acceptor strength in 22b, the 2,4-dinitrophenyl derivative 22a exhibits oscillating behavior at an electrode potential less negative than that required for the constitutional isomer 21a (Figure 20 21a, 22a). On the other hand, the 4-cyanophenyl derivative 23a displays increased sensitivity, which seems to be the result of the higher quantum yield of the photoreaction from 23a to 23b (Figure... 

The p-cyanophenyl derivative of [14lN4-diamide was prepared in a 19% yield from the p-cyanophenyl-substituted diethyl malonate (Morphy et al., 1988). Chiral cyclic diamides were prepared from chiral tetraamines in... 

As shown in examples 40 and 42, this synthetic principle can be applied to biselectrophilic systems with functions similar to 38 but in a higher oxidation state, such as o-formylphenyl or o-cyanophenyl derivatives of acetic acid 39 and 41 ... 

Reduction of a 7-(2-oxoethyl) derivative with NaBH4 in EtOH at room temperature gave 7-(2-hydroxyethyl)-2-(2-pyrimidinyl)perhydropyrido[l, 2-u]pyrazine (99MIP6). Reduction of 7-formyl-8-[(4-cyanophenyl)methoxy]-1,3,4,6,11,1 lu-hexahydro-2//-pyrazino[l,2-A]isoquinoline-l,4-dione with NaBH4 yielded a 7-hydroxymethyl derivative (98MIP7). 

Aminothiocarbonylphenyl)methoxy] derivative 384 was obtained from 8-[(4-cyanophenyl)methoxy]-2-cyclohexy 1-2,3,4,6,11,11 a-hexahydro-l/7-pyrazino[l,2-i]isoquinoline-l,4-dione by treatment with (EtO)2P(S)SH and one drop of H2O at room temperature for 17 h, then followed by addition of more H2O (98MIP7). Reaction of 8-[(4-aminothiocarbonylphe-nyl)methoxy] derivative 384 and MeCOCH2Cl yielded 8- [4-(4-methylthia-zol-2-yl)phenyl]methoxy derivative 385. 7-Bromomethyl derivative was prepared from the 8-hydroxymethyl-8-[(4-cyanophenyl)methoxy]-2-cyclo-pentyl-2,3,4,6,11,1 la-hexahydro-177-pyrazino[l, 2-i]isoquinoline-1,4-dione with PBr3 in CH2CI2 at room temperature. 7-[(l-Pyrazolyl)methyl] derivative was obtained from 7-bromomethyl derivative by treatment with pyrazole in the presence of NaH in DMF at 50 °C. 

Treatment of 8-[(4-cyanophenyl)methoxy]-7-formyl-2-cyclopentyl-2,3,4,6,11,1 la-hexahydro-l//-pyrazino[l,2-i]isoquinoline-l,4-dione with (Et0)2P(0)CH2C00Et and NaH in THF at 40 °C overnight, or with (2-pyridylmethyl)-, 4-[(ethoxycarbonyl)benzyl]-, (4-nitrobenzyl)-, and (meth-oxymethyl)triphenylphosphonium halogenide in the presence of KH in THF at room temperature gave 7-ethylene derivatives 386 (98MIP7). 

A comparison of the rate constant for photoisomerization of the unsubstituted 3-phenyl derivative (kT = 3 x 1010 sec-1) to that of the 3-(p-methoxy phenyl) derivative (kr = 1.5 x 1010 sec-1) indicates that the presence of the p-methoxy groups imparts no special stability to the intermediate responsible for isomerization even though cleavage of a cyclopropane bond is predominant. Clearly these results are inconsistent with an intermediate possessing electron-poor or electron-rich species such as would be obtained from heterolytic cleavage of the cyclopropane. On the other hand, the results are consistent with a biradical species as intermediate. Further evidence consistent with this conclusion was obtained in a study of trans-3-p-cyanophenyl-/ra w-2-phenyl-1 -benzoylcyclopropane,<82)... 

In addition, the following o-substituted arylacetic acid derivatives are suitable starting materials for the syntheses of 3(2//)-isoquinolinones o-formylphenyl-acetamides [71T4653 80JCS(P1)2013], o-cyanophenyl-acetic esters (68BSF3403), and o-cyanophenylacetic acid chlorides [68AG(E)484]. 

D. Horton, Y. Li, V. Barberousse, F. Bellamy, P. Renant, and S. Samreth, Synthesis of the 2- and the 4-monomethyl ethers and the 4-deoxy-4-fluoro derivative of cyanophenyl l.S-dithio-p-D-xylopyranoside as potential antithrombic agents, Carbokydr. Res. 249 39 (1993). 

Attempts to synthesize a condensed pentazine derivative by reaction of 6-chloro-l,2,4,5-tetrazino[3,2-a]isoindole (409) with sodium azide led to the isolation of 3-methyl-6-(2-cyanophenyl)-l,2,4,5-tetrazine (412) rather than the azide (410) or its valence tautomer (411) which contains a pentazine structure (Scheme 23) (82UP22100). 

Finally, the case of benzene derivatives having electron withdrawing substituents will be discussed. Experimental support for mein electron withdrawal by nitro and cyano groups has been found (3, (>, 20) in the photochemical solvolyses of nitrophenyl and cyanophenyl trityl ethers. For example, it is found that in the dark w-nitrophenyl trityl other (XLII) is essentially unreactive in 90% aqueous dioxanc while the para isomer (XLIII) solvolyzes smoothly this is in accord with ground-state, expectation, for p-nitrophenolate is a better departing anion than -nitropheiiolate. In contrast, on irradiation under the same conditions, m-nitrophcnyl trityl other solvolyzes rapidly to m-nitrophenol and tri-phenylcarbinol, as major products, while the para isomer s (XLIII) solvolysis is scarcely enhanced beyond experimental error. V similar... 

Derivatives of the 2-phenyl-1,3,4-oxadiazole-5-carboxylic acids give the usual reactions of acids on careful treatment.103 Thus the alcoholysis of the 5-acid chlorides with methanol or ethanol leads to the corresponding ester. Alkaline hydrolysis at 30° produces the carboxylic acid which on warming is decarboxylated to 2-phenyl-1,3,4-oxadiazole. Even a slight increase in the severity of the reaction conditions produces ring cleavage.103 The alkaline hydrolysis of 2-phenyl-5-(p-cyanophenyl)-1,3,4-oxadiazole with addition of H202 leads to 2-phenyl-5-(p-carboxamidophenyl)-1,3,4-oxadiazole.23... 

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