Quinoline, amination bromination

The effect of variation of the leaving group can be seen in several series. For the unactivated halonaphthalenes (Table IX), the series I Br > Cl is observed. The relation varies in the quinolines (Tables X and XI) and nitronaphthalenes (Tables XII, XIII, and XVI), but generally there is very little difference between these halogens. In activated compounds (Table XI, lines 6, 26, and 30), iodine is the least reactive halogen substituent as a rule, and bromine is sometimes more reactive than chlorine. The latter relation occurs in some aminations mentionedin Section II,D,2,b and as observed with the haloquinolines (Table X, lines 1 and 10). In amination (2-6 hr,... 

Charge transfer (CT) complexes, different from aromatic ketone/amine systems, such as quinoline-bromine, pyridine-bromine, tetrahydrofuran-bromine etc. have also been reported to behave as initiators of vinyl polymerization, particularly under photoactivation [65-68]. 

Perhaps the best known alkyne semi-hydrogenation catalyst is that developed by Lindlar which comprises calcium carbonate-supported palladium, modified by addition of lead acetate and, often, quinoline to improve selectivity [51]. Selective hydrogenation of 1-bromo-ll-hexadecyne (Eq. 8) has been shown to occur in high yield and without hydrogenolysis of the carbon-bromine bond, over Lin-dlar s catalyst treated with aromatic amine oxides such as pyridine A-oxide... 

Decarboxylation.—Direct decarboxylation of hindered geminal diesters has been achieved using amine bases (DBN Dabco). This attractive one step process generally gives good yields and avoids the use of both acidic and aqueous conditions. An improved method for the oxidative decarboxylation of vicinal diacids to olefins employs copper(i) oxide and 2,2 -dipyridyl in quinoline temperatures of 180 °C are however required. Excellent yields have been achieved in the decarboxylation of bridgehead carboxylic acids by sequential bromination and photochemical reduction in the presence of tri-n-butyltin hydride. 

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