Intramolecular silver® nitrate

Cyclization of a variety of y-allenic alcohols with silver nitrate proceeds by 5-exo cyclization to form 2-alkenyltetrahydrofurans (equation 87).205c 206 Little stereoselectivity is seen in cyclizations of secondary alcohols. Cyclization by intramolecular oxypalladation/methoxycarbonylation or oxymercuration followed by transmetallation and methoxycarbonylation also showed no stereoselectivity (equation 88 and Table 24, entries 1 and 2).50 207 However, cyclization of the corresponding r-butyldimethylsilyl ether derivatives with mercury(II) trifluoroacetate followed by transmetallation/methoxycarbonylation pro-... 

Finally, the Ag+ induced intramolecular alkyl coupling reaction of 9-BBN with alkaline silver nitrate in aqueous methanol as a route to os-bicyclo[3.3.0]octane is to be noted.118 ... 

Further work on the conformation of certain germacrane sesquiterpenoids has been performed using both X-ray analyses and the intramolecular nuclear Overhauser effect (n.o.e.). Complete details of the X-ray analysis of the silver nitrate adduct of germacratriene have been published. In addition to demonstrating its conformation as (222), this analysis correlates the known reactivity (to epoxidation) of the three double bonds (4=5 > 1=10 > 7=11) with their torsional strains. The X-ray analysis of a heavy-atom derivative of pyrethrosin (223) has revealed that some stereochemical adjustments are required with respect... 

Examples of the successful application of this method are the use of cop-per(II) acetate for the preparation of neutral complexes [Cu(SR)] (R = aryl, alkyl no base needed) (46), and the use of copper(II) nitrate for the synthesis of anionic species [Cu4(SPh))6]2 and [Cu5(SPh)7]2- (47, 48), as well as of the cationic species [Cu,(SC5H4NH)3]+ (49). The latter complex is interesting in that each thiolate ligand is neutral due to protonation of the pyridine nitrogen atom. Similarly, silver nitrate has been used to prepare several neutral alkyl-thiolato silver complexes (33). The use of copper(I) oxide was reported in the synthesis of a family of copper(I) arenethiolates containing intramolecularly... 

The treatment of a disulfide with ammonia, silver nitrate, and a ketone is a general one-step synthesis of sulfenimines.13 The disulfide 5, in an intramolecular reaction, affords13 the 1,2-benzisothiazole 6. 

When 5-methylene-2,3,4,5-tetrahydro-1 -benzothiepine (111) was subjected to ring expansion reaction conditions (treatment with silver nitrate in the presence of iodine in methanol), intramolecular attack by sulfur at the initially formed halomethyl group led to the bicyclo[3.2. Ijoctane intermediate (112), which yielded the benzothiophene derivative (113) without formation of any ring expansion products (Scheme 15) <89TL4279>. 

E)-Alkenes. The reaction of trialkylboranes with alkaline silver nitrate (2, 368) to form coupled alkanes has been used to convert 1,2-diorganoboranes from internal alkynes into (E)-alkenes. The reaction is considered to involve an intermediate diradical that couples intramolecularly to the alkene. 

It has been shown that functionalized pyrroles can be efficiently prepared using a two-step sequence. This sequence involves the propargylation of secondary enami-nones using -BuLi and propargyl bromide, followed by intramolecular hydroamination catalyzed by silver nitrate (Robinson et al. 2005a). The hydroamination can be carried out at room temperature (overnight) or in a domestic microwave oven (60 s). 

Silver nitrate potassium tert-butoxide Intramolecular C-alkylation of ketones Tris-bridged cyclophanes... 

Intramolecular nitrogen attack in propargylated enaminones allows silver-catalyzed access to functionalized pyrroles. This Ag-promoted hydroamination can also be used to obtain A bridgehead pyrroles. Silver nitrate-mediated cyclization of allenylamines, available from Uthiated alkoxy allenes and imines or through reaction of l-(lV-carbamoyl)-alkylcuprates with propargyl substrates, provides access to 2,5-dihydropyrrole derivatives. Iminoallenes can be used for the synthesis of substituted p)moles in moderate yields in the presence of potassium carbonate. ... 

Heck intramolecular cyclization. Silver carbonate or nitrate was added originally to tandem Heck arylation reactions to depress alkene isomerization, but they also improve selectivity in the -elimination step. Grigg et al.1 have used a number of useful additives such as triethylammonium chloride, sodium formate (15, 248), phenylzinc chloride, as well as silver(l) and thallium(I) salts. In fact, thallium(I) salts... 

Fig. 26. Comparison between radial distribution functions for 3 M silver(I) nitrate in aqueous and in DMSO solutions. Intramolecular interactions of the solvent molecules have been removed. The derived structures for the solvated silver(I) ion in the two solvents are shown.

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