Allylic mercurial

In the present study, the Jg g values in the allyl alkali metal compounds are near 60 hz for the K and Cs compounds, and a little lower for the Li compound, table I. Allyl mercury is not a delocalized system, and if any exchange occurs between the two ends of the allyl radical it is slow on the NMR time scale. Consequently and Jg Y are measurable and are h2 and 69 hz... 

In this connection, our finding that the allylic mercury intermediate represents the only isolated product following reaction in THF, CH2CI2, or HMPA is pertinent. The generation of this species appears to be rapid in all media. The ensuing step in which Hg(II) is reduced to Hg(O) likely serves as the rate-determining step. If so, the role of nonpolar benzene may be to stabilize the transition state and accelerate the overall rate. No allylic alcohol having an exocyclic double bond was formed, a feature that hints to the possible operation of thermodynamic control. 

The terms in equation (23) which are independent of the acid concentration show little or no solvent isotope effect. This and considerations following from the Bronsted Catalysis Law make it unlikely that these terms represent cleavage of the complexed substrate by water. A ratedetermining, unimolecular rearrangement from the a- to the v-allylic mercurial was suggested. Oxidative cleavage of some sort is another possibility. 

On the basis of this and odier evidence allylic mercury(II) acetates are believed to be the reaction intermediates in all allylic oxidations with mercury(II) acetate. The isolation of the less stable secondary... 

The authors suggest this method as a preparative procedure for allyl-mercury compounds starting from olefins and dienes via the 7r-allylpalla-dium complexes. 

Allyl cyanide. Into a 1 5 litre three-necked flask (1), provided with a mercury-sealed stirrer and two long double surface condensers, place 293 g. (210 ml.) of freshly-distilled allyl bromide, b.p. 70-71° (Section III, 35) and 226 g. of dry cuprous cyanide (Section 11,50,3, Method 1), Remove the mercury-sealed stirrer and replace it by a tightly fitting... 

The employment of non-protic electrophiles for the foregoing type of cyclizations as illustrated in Scheme 8 has the particular merit of leaving a useful point of departure for further transformations. Comparable cyclizations of 2-allyl-3-aminocyclohexenones with mercury(II) acetate are preceded by dehydrogenation to the corresponding 2-allyl-3-aminophenol as shown in Scheme 9 82TL3591). The preferred direction of cyclization depends upon the nucleophilicity of the amino group. 

The cyclized analog of meralluride is prepared by a similar synthesis. Thus, condensation of camphoric acid (42) (obtained by oxidation of camphor) with ammonia gives the bicyclic succinimide (44). Reaction with allyl isocyanate followed by ring opening and then reaction with mercuric acetate affords the mercury derivative (45) as the acetate rather than the hydroxide as above. Reaction with sodium chloride converts that acetate to the halide (46). Displacement on mercury with the disodium salt of thioglycollic acid affords the diuretic mercaptomerine (47). ... 

The reaction mixture was cooled, treated with about 100 ml of water, and the oily organic layer which formed was removed, washed with water and dried over anhydrous magnesium sulfate. The dried oily organic material was fractionally distilled in vacuo, and diethyl allyl (1-methyl-2-pentynyl) malonate boiling at 105° to 107°C at the pressure of 1 mm of mercury was recovered. 

The combined ether extracts were washed with 5% aqueous sodium bicarbonate solution, dried over anhydrous sodium sulfate, and fractionally distilled in vacuo. The fraction boiling at about 145° to 150°C at the pressure of 0.5 mm of mercury, weighing 61 g and consisting of 1-methyl-5-allyl-5-(1-methyl-2-pentynyl) barbituric acid, was collected. The only distillate was substantially pure, and could be used as such In pharmaceutical preparation or a salt could be prepared therefrom according to the procedures disclosed hereinafter. On standing, the oil crystallized. The crystalline 1-methyl-5-allyl-5-( 1-methyl-2-pentynyl) barbituric acid melted at about 60° to 64°C after recrystallization from dilute ethanol. 

FIGURE 10. Voltammetric curves of fully aliphatic allylic sulphones (c = 3 x 10-3 M) in DMF/TBAP 0.1 m electrolyte, stationary mercury electrode, sweep rate 10 mV s—1 (a) and (b) curves in aprotic DMF (c) response of the sulphone, (b) with phenol 10-2 m (after Reference 26). 

To circumvent some of the above-mentioned drawbacks of sulfur-based mercury chemodosimeters, a system based on the alkyne oxymercuration of 58 has been developed (Fig. 22) [146]. 58 shows high selectivity, a limit of detection of ca. 8 ppm, resistance against strong oxidants, and a positive reaction even in the presence of cysteine, which is known to form stable mercury complexes and is used for the extraction of mercury from tissue samples. Another metal that is well-known for its catalytic ability is palladium, catalyzing different reactions depending on its oxidation state. Since this metal is toxic, assessment of the maximum allowable concentration of Pd in consumer products such as pharmaceuticals requires highly sensitive and selective detection schemes. For this purpose, indicator 60 was conceived to undergo allylic oxidative insertion to the fluorescein... 

Considering that /Tarninornercury(II) tetrafluoroborates are polar enough to undergo nucleophilic attack by the lone electron pair of an amine, ether or alcohol in the case of the 1,3-cyclooctadiene, 179, it has been assumed that the first formed 1,4-adduct can give the reaction product by displacement of mercury by amine with direct participation of the nucleophile in an assisted breakage of the anti C—Hg bond (path a) or by spontaneous reduction of mercury in the intermediate allylic organomercurial (path b) (equation 157). 

Furthermore, more recent work about the monoalkoxymercuration of a series of conjugated dienes with different mercury salts has shown157 that the alkoxymercuration of these compounds proceeds in two steps, the first being the formation of 1,2-adducts in which, with the exception of the mercuration of a-terpinene, the alkoxy group occupies the allylic position. The 1,2-alkoxymercurials are in equilibria with the corresponding... 

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