Electron-donating groups, OMe

The chlorine can be disconnected with the alternative polarity via the diazonium salt to amine (19) (guideline 4), The amino group is more powerfully electron-donating than OMe so we can disconnect the NO group. The amino group is itself derived from another nitro group. 

The neutral and acid-catalysed mechanisms of hydrolysis of formamide, HCONH2, have been revisited and a comparison made between ab initio, semiempirical and DFT results Ab initio MO calculations on the alkaline hydrolysis of para-substituted acetanilides (135) in the gas phase have shown that the activation energy depends on the nature of electron-withdrawing groups (e.g. X = NO2, CN, Cl) but is invariant for electron-donating groups (X = NH2, OMe). ... 

As expected, the basicity of concave pyridine bislactams 3 (Structures 1) and pyridine bissulfonamides 13 (s. Scheme 3) was enhanced by 4-substitution with electron-donating groups like OMe or NEt2 (ca. 1 pK unit for OMe, more than 3 pK units for NEt2 [12, 32]). But also the nature of the chains X and Y had a strong influence on the basicities. The basicities of 4-/f-substituted pyridines 3 vary by more than two orders of magnitude [12]. However, when the basicities of the concave pyridines 3 are compared with non-concave pyridines they cover the same range of basicity. 

Case 1. If X is an electron-donating group it becomes the C-6 substituent in the indole ring. The substituent deactivates C-3 of the quinone to nucleophilic attack. Attack at C-5 is preferred to C-6 because of the more electrophilic character of the C-l carbonyl. Examples X = OMe, OH. 

Okada et al. (838), from comprehensive studies of the reactions of 3-substituted pyrazine 1-oxides (12) with phosphoryl (thionyl and sulfutyl) chloride, concluded that when the substituent was an electron-withdrawing group (e.g., methoxy-carbonyl) the substitution would be at the 5-position to give the 2,6-disubstituted pyrazine (e.g., 13, R = COOMe), whereas the 2-chloro compound (e.g., 14, R = NHj) would be obtained when the substituent was electron-donating (e.g., amino). When a weak electron-donating group (e.g., methoxy) was present both types of pyrazines (e.g., 13 and 14, R = OMe) would be formed. 

The thiomethyl catalyst (35) gives the (I )-l R,2R enantiomer of 1-phenylcyclohexene between temperatures of 0 °C and temperatures of 50 °C (Table 5.11, entries 3,8,12),but at —78 °C the ( )-lS,2S enantiomer is formed (Table 5.15, entry 18). This we believe is due to the sulphide being oxidized to the sulphone at temperatures above 78 °C, therefore altering the electronic nature of the catalyst. Catalyst (37), which also has an electron-donating group at C4 (OMe), cannot be altered by the... 

Nitroarenes display strong absorption in the near-UV region and are efficiently photoreduced.1187 An intermolecular version of this reaction is depicted in Scheme 6.187. The photoreduction is initiated by hydrogen atom abstraction. Substituted nitrobenzenes 393, where X is an electron-donating group (X = p-Me, /)-OMe) or nitrobenzene itself (X = H) are photoreduced in the presence of propan-2-ol to the corresponding... 

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