Hydrolysis, bromine

Tropolone has been made from 1,2-cycloheptanedione by bromination and reduction, and by reaction with A -bromosuccinimide from cyolo-heptanone by bromination, hydrolysis, and reduction from diethyl pimelate by acyloin condensation and bromination from cyclo-heptatriene by permanganate oxidation from 3,5-dihydroxybenzoic acid by a multistep synthesis from 2,3-dimethoxybenzoic acid by a multistep synthesis from tropone by chlorination and hydrolysis, by amination with hydrazine and hydrolysis, or by photooxidation followed by reduction with thiourea from cyclopentadiene and tetra-fluoroethylene and from cyclopentadiene and dichloroketene. - ... 

Synthetic routes that access appropriately substituted thienobenzazepines are also quite important for medicinal chemistry stracture activity relationship studies, and many involve similar bond connectivity strategies. One notable example employs the use of conunercially available 4-methyl-3-nitrophenol (Scheme 6.3). Methylation of the phenol followed by bromination, hydrolysis, and oxidation of the benzylic alcohol afforded aldehyde 9 in quantitative yield. Treatment of this aldehyde with 5-lithio-2-methylthiophene provided, after dehydroxylation, nitro intermediate A in good overall yield. Reduction of the nitro functionality and treatment with phosgene presented the corresponding isocyanide which upon cychzation using aluminum trichloride in a Friedel-Crafts fashion afforded the... 

The pyrimidine nucleosides from ribonucleic acid (uridine and cytidine) present a more formidable problem, since they cannot be hydrolyzed by dilute mineral acid, and the use of concentrated acid usually destroys the sugar moiety. It was observed, however, that simultaneous bromination, hydrolysis, and oxidation of cytidine (with bromine-hydrobromic acid) yields 5-bromouracil plus D-ribonic acid.60 Since cytidine can be deaminated to uridine with nitrous acid,61 both of these pyrimidine nucleosides must... 

On the other hand, pure (-)-yatein 43, which was obtained from recrystallization of the optically enriched material furnished by path b, was sequentially converted as above to (+)-isostegane 44 and (-)-stegane 45, the latter being transformed into (-)-steganacin 2 in 61% yield by stepwise bromination, hydrolysis and acetylation [39],... 

As in the selenium case (Scheme 17) the oxidation of alkyl phenyl telluride with excess MCPBA in the presence of alcohols results in a facile substitution of a PhTe moiety by an alkoxy group. The reaction is assumed to proceed via a similar tellurone-MCPBA adduct intermediate. Oxidation of cycloalkyl telluride (61) was accompanied by ring contraction to produce an acetal (62), < while the bromination-hydrolysis method affords the allylic ether by telluroxide elimination (Scheme 22). ... 

Attempts to measure the rates of bromine hydrolysis directly attained very limited success . Formation of the intermediate BrjOH was proposed . ... 

The ring contraction rearrangement of alicyclic a-diketones is much more valuable from the synthetic viewpoint e.g. equation 4). There are several routes available for the synthesis of a-diketones from monoketones. These include direct oxidation using selenium dioxide permanganate or osmium tetrox-ide addition across the double bond of an enone followed by base-promoted elimination of water bromi-nation to give the dibromo ketone followed by hydrolysis condensation with 4-nitroso-/V,/V-dimethylaniline followed by acidic hydrolysis — but there are many others. The bromination-hydrolysis route has been extensively studied by Wallach." The conversion of menthone into 1-hydroxy-... 

Fig. 7 A sequence of free-radical bromination, hydrolysis, reaction with PCI5 and addition of Cl, to double bonds yields 1,2,4,5,6,910-heptachlorodecane [8]...

On bromination/hydrolysis, camphoric acid (69) is oxidized and rearranges to give camphanic acid (70), containing a free carboxylic group and a lactone moiety. Thus, from (+)-camphoric acid [(+)-69], (—)-camphanic acid [(-)-70] is obtained70. Both enantiomers of camphanic acid, as well as the acid chlorides, are commercially available. 

Irradiation fs. a. under LiClOJ Selective O-debenzylation by bromination-hydrolysis... 

Rastogi, R.P., Mishra, G.P., Das, 1., Sharma, A. Sequential oscillations in bromine hydrolysis controlled oscillators in a closed reactor. J. Phys. Chem. 97, 2571 (1993)... 

According to the critics of the Explodator the most problematic step in our new scheme is the chemical realization of process (E2). Thev suggest that (E2) in fact goes through bromine hydrolysis (Rl)... 

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