Heterocycles silver© nitrate

Alkylation of protonated nitrogen heterocycles (e.g., pyridines, quinolines) can be accomplished by treatment with a carboxylic acid, silver nitrate, sulfuric acid, and ammonium peroxydisulfate. The R group can be primary, secondary, or tertiary. The attacking species is R% formed by " ... 

The same pattern of activity is maintained in a closely related analogue. Condensation of amino-sulfonamide 201 with aldehyde 202 affords the saturated heterocyclic system (203) oxidation with silver nitrate leads to the antihypertensive agent pazoxide (204). 49... 

An extension of the research on silver complexes with Lewis base-functionalized mono(A-heterocyclic carbene) ligands has been made toward the better-studied and stronger coordinating phosphine systems. The reaction of a diphenylphosphine-functionalized imidazolium salt with silver oxide in dichloromethane affords a trinuclear silver carbene complex 50, as confirmed by electrospray-ionization mass spectrometry.96,97 Metathesis reaction of 50 in methanol using silver nitrate gives 51 in 33% yield. The crystal structures of 51 were found to be different when different solvents were used during crystallization (Scheme 12).97 One NO3- anion was found to be chelated to... 

A novel type of ligands are tertiary stibines containing heterocyclic aromatic groups (Y-2-C4H3)3Sb (Y = S, O, or NMe) which with silver nitrate form polymeric 2 1 complexes, [ (Y-2-C4H3)3Sb 2AgN03]x.56... 

Cha and co-workers reported that the silver nitrate-mediated heterocyclization of the diastereomerically pure aminoallene 192 gave the desired quinolizidine 193 and 194, both possessing the E double bond geometry, as a 7 1 mixture of diastereomers (Scheme 19.36) [43]. Diastereomeric transition states 197 and 198 were proposed. The quinolizidine 201 was expected to form predominantly from 199. They pointed out that interestingly, the cyclization of a 1 1 mixture of diastereomers of 192 gave a 1 2 mixture of 193 and 194. Compound 193 was successfully converted to the target clavepictine A (195) and B (196). 

Allenes can also act as the -participant in electrophilic heteroatom cyclizations. Reviews of electrophilic additions to allenes discuss early examples of this type of cyclization.ld le-202 Numerous examples of cyclizations of a-functionalized allenes, including carboxylic acids, phosphonates, sulfinates and alcohols, to form five-membered heterocycles (equation 84) are cited in these reviews. The silver nitrate-mediated conversion of ot-allenic alcohols to 2,5-dihydrofurans203 has recently been applied to trimethylsilyl-substituted systems.204... 

In 2005 and 2006, Mori et al. reported the arylation of heterocycles with aryl iodides using palladium dichloride complexes as catalysts and silver nitrate or fluoride as activators (Scheme 10.50). The best coupling conditions were obtained with a combination of silver nitrate and potassium fluoride.82... 

It was recently shown that the addition of metal salts dramatically increased the diastereoselectivity on sulfinyl ketimine enolates, which provides a rapid route to syn- and anri-1,3-amino alcohols (Scheme 3, eq 1). For two other recent examples, a silver nitrate (AgNOsj/LDA combination has been used in the formation of selenium containing heterocycles as potential antitumor agents (Scheme 3, eq 2), while an LDA/HMPA combination was used to fragment aromatic thioacetals to form unsymmetrically substituted thiothionophthalicanhydrides (Scheme 3, eq 3). ... 

In the same way that the controlled release of silver ions is important in the antibacterial activity of silver nitrate and silver(I) n-pincer-type heterocyclic carbene complexes, the release of carbon monoxide in a controlled... 

Synthesis of compound 68 by oxidative decarboxylation of adamantane carboxylic acid is described in [25], Initially, for the synthesis of 2-(l-adamantyl)benzimidazole (68), adamantan radical was obtained in sulphuric acid diluted by silver nitrate in the presence of ammonia persulfate. Then, the synthesized radical was inserted directly into the heterocycle. After N-methylation, 2-(l-adamantyl)benzimidazole (68) was transferred in l-methyl-2-(l-adamantyl)-benzimidazole (79). The experiments carried out on chicken embryo revealed high antiviral activity of both obtained compounds [25] ... 

Methylseleno esters are readily available in excellent yields by the reaction of Dimethylaluminum Methylselenolate with O-alkyl esters. These selenoesters will acylate reactive arenes (eq 69) and heterocyclic compounds (eq 70) when activated by CuOTf, a selenophilic Lewis acid. Of the potential activating metal salts tested, (CuOTf)2 QHe is uniquely effective. Mer-cury(ll) or copper(l) trifluoroacetates that are partially organic-soluble, as well as the corresponding chlorides, silver nitrate, and... 

Crystal structures of 1-methylcytosine and 1-methylthymine complexes have been determined as aids to the understanding of Ag binding to polynucleotides. In (1-methylcytosine)silver(I) nitrate, a centrosymmetric dimer was present in which the N heterocycles were bridged by two Ag" ions. Within these dimers, there were two strong metal-ligand bonds, (Ag—N = 222.5, Ag—O = 236.7 pm) and an eight-membered ring (8) resulted. 

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