Aminomercuration intramolecular

Another synthetic route to 3-methylhasubanan (43), proposed by Lattes et al. (74), consists of the intramolecular aminomercuration (75) of amino-ethylphenanthrene 27. The key intermediate 27 was treated with mercury(II) acetate in THF/water to yield 9-acetoxymercury-3-methoxyhasubanan (46), as depicted in Scheme 3, and then the reaction product 46 was successively treated with benzyltriethylammonium chloride, sodium hydroxide, and sodium borohydride to furnish the target, 3-methylhasubanan (43) (74). 

Bicyclic206 and spirocyclic207 amines are also readily prepared by intramolecular aminomercuration-demercuration (equations 153 and 154). 

Related intramolecular aminomercurations of cyclic guanidine derivatives have been studied in some detail,2 0 but are primarily useful for the synthesis of bicyclic heterocycles (equations 127 and 128). Cy-clizations of allylic isothiouronium salts have also been reported (equation 129).260b,260e... 

Intramolecular aminomercuration.1 The key step in a synthesis of ( —)-deoxoprosophylline (4), a piperidine alkaloid, from (S)-serine (1) is aminomercuration of 2. This step proceeds stereoselectively to give 3 with only traces of the C8-epimer. Hydrolysis of the acetonide group furnishes 4. 

An example of intramolecular aminomercuration has been reported by Weimeb as part of the synthetic strategy to the tricyclic nucleus of madangamine A - an alkaloid that shows cytotoxicity toward a number of tumor cell lines (equation 15). Pearson has recently reported the first example of an azidomercuration involving aliphatic azides (see equation 16) according to a protocol that exhibits wider applicability and is, therefore, more convenient than the analogous acid-promoted Schmidt reaction. ... 

The 6-bromodeoxy-tri- O -benzyl-pyranoside 44 was heated in a mixture of acetic acid and zinc dust to give 45, which directly underwent reductive amination using benzylamine and NaBH3CN to afford 46 (Scheme 9). Intramolecular aminomercuration of 46 with mercuric trifluoroacetate afforded bromomercurials 48 (61%) and 47 (39%). Reductive... 

Intramolecular aminomercuration [(479) - (480)] has been studied as a function of changes in various parameters, including length of chain and effects of substituents on the nitrogen, in the chain, and on the double bond. ... 

Mercuric chloride-sodium tetrahydridoborate N-Heterocyclics from ethyleneamines via intramolecular aminomercuration... 

Most cyclizations to form five-membered rings involve the 5-exo mode of cyclization. An exception has been reported in the intramolecular sulfenoamination of 3-alkenylamines used in the synthesis of pyrrolidine alkaloids (equation 102).215 229 Other examples include the aminomercurations of Af-sub-stituted-l-amino-3-butenes162,23° and the methylsulfenilium ion-initiated cyclization of 0-(2-propenyl)-/V-tosylaniline 231... 

In this connection, intramolecular Michael addition of 0-carbamates to a,3-unsaturated esters (Scheme 60)," iodo cyclization of allylic and homoallylic trichloroacetamidates" or aminomercuration of alkenic carbamates" has been used for the preparation of amino alcohols. 

On the basis of these results, cyclization should proceed in two steps, the second one being the intramolecular amino (or oxy) mercuration of the second double bond. For geometric reasons, the reaction which leads to mercurial 203 from 202 is expected to be kinetically favored since it does not require any conformational change on going to the transition state, and hence this isomer should be obtained under kinetic control . The mercurial 204, arising from the intermediate 202a, in equihbrium with 202, should give instead the more stable 13.3.11 isomer 201 (or 199), which should therefore predominate under thermodynamic control, i.e. in reversible aminomercuration of 3 (equation 167). 

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