Olefins solvomercuration

Mercury(II) trifluoroacetate is a good electrophile that is highly reactive toward carbon-carbon double bonds [52, 53, 54] When reacting with olefins in nucleophilic solvents, it usually gives exclusively mercurated solvoadducts, but never products of skeletal rearrangement Solvomercuration-demercuratton of alkenes with mercury(II) trifluoroacetate is a remarkably effective procedure for the preparation of esters and alcohols with Markovnikov s regiochemistry [52, 5J] (equation 24)... 

Fig. 1.11. Net reaction (a) for the hydration of olefins (R = CH3, R = H) or (b) for the addition of alcohol to olefins (R = CF3, R = alkyl) via the reaction sequence (1) solvomercuration of the olefin (for mechanism, see Figure 3.37 regioselectivity Figure 3.38) (2) reduction of the alkylmercury compound obtained (for mechanism, see Figure 1.12).

Solvomercuration of Olefins Hydration of C=C Double Bonds through Subsequent Reduction... 

Fig. 3.37. Hydration of a symmetric olefin through solvomercuration/ reduction.

Fig. 3.38. Regioselective hydration of an asymmetric olefin via solvomercuration/reduction.

Besides H20, simple alcohols or acetic acid can also be added to olefins by solvomercuration/reduction. Figure 3.39 shows MeOH addition as an example. The regioselec-tivities of this reaction and of the H20 addition in Figure 3.38 are identical. 

Fig. 3.39. Regioselective methanol addition to an asymmetric olefin via solvomercuration/ reduction.

The solvomercuration of alkenes has an important synthetic valne since it allows the asymmetric functionalization of olefins. Although a large number of organomercurials have been isolated from these reactions, more commonly, they are reduced with alkaline NaBELi to yield the corresponding metal-free organic species (see Section 4.1). In this way, olefins can be converted into a wide range of organic species such as alcohols, ethers, and amines. 

Comersion of olefins into ethylene ketals. Hunt and Rodchcaver have described a method for conversion of olefins into ethylene ketals. Three steps are involved I) solvomercuration, 2) transmetalation, and 3) decomposition of the organopalladium intermediate. 

Amides.1 The solvomercuration-demercuration of terminal olefins or cyclic olefins with acetonitrile and mercury 11) nitrate followed by reduction of the intermediate organomercury compound affords amides, hydrolyzable to amines. Neither mercuric acetate nor mercuric trifiuoroacetate is satisfactory in this reaction. Preliminary attempts to use a tertiary olefin failed. 

The chain terminal ethoxy group of compound 41 has been introduced by means of the solvomercuration-demercuration method (Brown, 1967 Brown and Min-Hon Rei, 1969). This process, based on the mercuration of olefin with mercuric... 

Brown, H. C. and Geoghegan, P. J., Jr. (1970) Solvomercuration-demercuration. 1. Oxymercuration-demercuration of representative olefins in an aqueous system. Mild procedure for the Markovnikov hydration of the carbon-carbon double bond. J. Org. Chem. 35, 1844-1850. 

Anti-Markownikov hydrohalogenation is obtained in 75% yield by treating the olefin with an organoborane, effecting transmetallation with HgO, and treating the resulting organomercurial with Bra." Intermediates need not be purified. The solvomercuration-demercuration procedure effects Markownikov hydration of olefins in 77-98%... 

Olefins are converted into ethylene acetals (494) by a series of reactions involving (a) solvomercuration of the olefin, (b) formation of a a-bonded organopalladium derivative by a transmetallation reaction with palladium... 

In contrast, the mercurial enones (89) (obtained by specific solvomercuration of the corresponding pendant terminal olefins) are isolated, and on treatment with sodium trimethoxyborohydride are reductively cyclized to (90). Alkynes... 

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