Bridged polycyclic of University of Colorado group.  LXXV.  Reduction of organomercurials.  Stereospecific replacement of mercury by deuterium

Jensen, Frederick R.; Miller, John J.; Cristol, Stanley J.; Beckley, Ronald S.

doi:10.1021/jo00799a024

Cited by 43 publications

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“…The inability to capture the presumed radical intermediate involved in hydride reductions of the α-mercurio iminium ions led us to seek evidence for the presence of the mercury(II) group in the Schmidt reaction product. Specifically, reduction with sodium borodeuteride should replace the mercury with deuterium (Scheme , 54 → 55- d 1 → 11- d 2 or 53- d 2 ), a well-known process in organomercury chemistry. − The mercury-promoted Schmidt reaction of 10 was thus followed by reduction with sodium borodeuteride, producing only the monodeuterated product 11a , the result of deuteride reduction at the iminium ion carbon (i.e., R 1 = D). No evidence for a second deuterium at R 2 , the position presumably occupied by mercury, was found, i.e., no 11b (R 1 = R 2 = D) was formed.…”

Section: Resultsmentioning

confidence: 99%

Azidomercurations of Alkenes: Mercury-Promoted Schmidt Reactions

2000

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Azides bearing a suitably disposed alkene, when treated with either mercuric perchlorate or mercuric trifluoromethanesulfonate, produce bicyclic iminium ions. This new version of the Schmidt reaction proceeds by capture of the mercuronium ion intermediate by the azide to produce an aminodiazonium ion, which suffers a 1,2-shift to give an iminium ion (e.g., 10 --> 16 --> 17 --> 18). Reduction of the iminium ion may then be carried out to produce an amine. Compared to earlier work on the protic acid-promoted intramolecular Schmidt reaction of azido-alkenes, the mercury-promoted Schmidt reaction has several advantages. First, the acid-promoted Schmidt reaction of azido-alkenes requires that the intermediate carbocations be tertiary, allylic, benzylic, or propargylic. The mercury-promoted method has no such limitation; thus even 1,2-disubstituted alkenes may be used. Second, the mercury-promoted method is milder, allowing the presence of acid-sensitive functionality. The protic version, typically employing trifluoromethanesulfonic acid, is limited in its functional group tolerance. Third, whereas carbocation rearrangement is often observed prior to cyclization/rearrangement in the acid-promoted Schmidt reaction, the mercury-promoted method avoids this problem. Fourth, the presence of the mercurio group during the rearrangment may alter the regioselectivity of the 1,2-migration. Finally, the mercury-bearing iminium ions that are the result of the Schmidt reaction were found to be sensitive to protodemercuration, precluding their use in other transformations.

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Section: Resultsmentioning

confidence: 99%

Azidomercurations of Alkenes: Mercury-Promoted Schmidt Reactions

2000

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“…On the other hand, sodium amalgam provides a valuable method for the stereospecific replacement of mercury by deuterium [65]. Although hydrazine has been employed as a reducing agent, it generally gives poor yields.…”

Section: Nabh4mentioning

confidence: 99%

Organomercury Compounds in Organic Synthesis

Larock

1985

Reactivity and Structure Concepts in Organic Chemistry

103

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Organomercurials have been known since 1850 and many synthetic routes to these compounds presently exist. The ability of these compounds to accommodate a wide variety of functional groups and to tolerate quite diverse reaction conditions makes them attractive as synthetic intermediates. While the ~~lv~mercuration-demercuration and divalent carbon transfer reactions remain the most widely used of the organomercurial reactions, a number of new synthetic procedures employing organomercurials have been developed in recent years. Many of these involve transmetallation reactions with palladium salts.

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“…Reductive demercuration reactions of alkylmercury halides by metal hydrides, such as sodium borohydride, appear to proceed via free radi cal chain processes [12]. The loss of stereochemical integrity [13][14][15][16], the observation of the rearranged product, 1,1,2-triphenylethane, from the sodium borohydride reduction of 2,2,2-triphenylethylmercury [17] and the efficient trapping of the alkyl radical intermediates by molecular oxygen [18] are evidence introduced to support the radical mechanism in these reactions. Scheme II outlines the most general accepted mechanism for the reduction of organomercurials.…”

Section: Free Radical Substitution Reactions Of Alkylmercury Halidmentioning

confidence: 99%

Free-radical chain reactions of organic mercury and tin compounds

Tashtoush

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Bridged polycyclic of University of Colorado group. LXXV. Reduction of organomercurials. Stereospecific replacement of mercury by deuterium

Cited by 43 publications

References 0 publications

Azidomercurations of Alkenes: Mercury-Promoted Schmidt Reactions

Azidomercurations of Alkenes: Mercury-Promoted Schmidt Reactions

Organomercury Compounds in Organic Synthesis

Free-radical chain reactions of organic mercury and tin compounds

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