Quaternary Nitrogen Heterocycles. VII. Reactions of some Tricyclic Heteroaromatic Cations in Basic Solutions

1974 ◽  
Vol 52 (6) ◽  
pp. 981-987 ◽  
Author(s):  
John W. Bunting ◽  
William G. Meathrel
Keyword(s):  
Nitrogen Heterocycles ◽  
Resonance Energy ◽  
Nucleophilic Attack ◽  
Quaternary Nitrogen ◽  
Basic Solutions ◽  
Methoxide Ion

Pseudobase formation and methoxide ion addition have been investigated spectroscopically for some N-methylacridinium, -phenanthridinium, and -benzoquinolinium cations. Susceptibility to nucleophilic attack decreases in the order 10-methylacridinium (pKROH = 9.86) > 5-methylphenanthridinium (pKROH = 11.94) > 1-methyl-5,6-benzoquinolinium ≈ 1-methyl-7,8-benzoquinolinium (pKROH &([a-z]+); 14). A qualitative correlation of pKROH with loss of resonance energy upon pseudobase formation is shown to exist. For the 9,10-dimethylacridinium cation, the C-9 pseudobase (or methoxide adduct) is the kinetically preferred product in basic solutions but this is subsequently converted to the thermodynamically more stable anhydrobase. With the corresponding 9-ethyl- and 9-benzyl-10-methylacridinium cations, the pseudobase, rather than the anhydrobase, seems to predominate at equilibrium.

Mechanisms of Nucleophilic Attack at Carbon-Nitrogen Double Bonds. The Reaction of Benzohydrazonoyl Compounds With Methoxide Ion

1995 ◽  
Vol 48 (12) ◽  
pp. 2041 ◽  
Author(s):  
JE Rowe ◽  
DA Papanelopoulos
Keyword(s):  
Nucleophilic Attack ◽  
Rate Data ◽  
Double Bonds ◽  
Elimination Mechanism ◽  
Methoxide Ion

Rate data for the reaction of a number of benzohydrazonoyl compounds with methoxide ion are reported. The stereochemistry of the products was determined by h.p.l.c. The mechanism of the reactions and the stereochemistry of the products resulting from an addition-elimination mechanism are discussed.

Quaternary Nitrogen Heterocycles. I. Equilibrium and Spectral Data for Pseudobase Formation by the N-Methyl Cations of Diazanaphthalenes

1972 ◽  
Vol 50 (6) ◽  
pp. 917-931 ◽  
Author(s):  
John W. Bunting ◽  
William G. Meathrel
Keyword(s):  
Spectral Data ◽  
Ring Opening ◽  
Lithium Aluminum Hydride ◽  
Equilibrium Constants ◽  
Nitrogen Heterocycles ◽  
Aluminum Hydride ◽  
Ionization Constants ◽  
Lithium Aluminum ◽  
Quaternary Nitrogen ◽  
Hydride Reduction

Equilibrium constants have been measured at 25° for the formation of pseudobases from the 2-methyl-phthalazinium, 1-methylquinoxalinium, 1-methyl- 1,5-naphthyridinium, 6-methyl-1,6-naphthyridinium, 7-methyl-1,7-naphthyridinium, 1-methyl-1,8-naphthyridinium, 1-methyl-3-nitroquinolinium, and 2-methyl-4-nitroisoquinolinium cations. Ionization constants have also been obtained for ionization of some of these pseudobases to alkoxide anions. For each cation the site of hydroxide attack has been determined by comparison of the u.v. and p.m.r. spectra of the pseudobases, the corresponding methoxide adducts, and the lithium aluminum hydride reduction products. In all cases, except for the 1-methylquinoxalinium cation, only one major pseudobase species is present in solution, and ring-opening does not occur to any appreciable extent. The pseudobase of the 1-methylquinoxalinium cation exists in equilibrium with a considerable amount of its covalent hydrate from addition of water across the C3—N4 bond.

The reactivity of cyclic germoxycarbene complexes of manganese and rhenium towards nucleophiles

1976 ◽  
Vol 54 (16) ◽  
pp. 2557-2562 ◽  
Author(s):  
M. J. Webb ◽  
W. A. G. Graham
Keyword(s):  
Infrared Spectra ◽  
Empirical Formula ◽  
Sodium Methoxide ◽  
Lithium Bromide ◽  
Subsequent Treatment ◽  
Nucleophilic Attack ◽  
Tetraethylammonium Bromide ◽  
Carbene Complexes ◽  
Methoxide Ion

Several acylate salts and noncyclic carbene complexes of manganese and rhenium, containing organogermanium ligands, have been prepared via the reactions of the cyclic germoxycarbene complexes of empirical formula Ph2GeM(CO)4COMe (M = Mn, Re) with the nucleophiles methyllithium or methoxide ion. In each case the observed product could be rationalized in terms of nucleophilic attack at germanium. Treatment of Ph2GeRe(CO)4COMe with methyllithium, followed by ethylation with aqueous Et3OBF4, afforded cis-Ph2MeGeRe(CO)4C(OEt)Me. The manganese analog of this product could be obtained if excess methyllithium were used in the first step. The use of a deficit of methyllithium, however, followed by ethylation, yielded cis-Ph2FGeMn(CO)4C(OEt)Me. Solution infrared spectra have indicated that lithium methoxide and lithium bromide impurities in the methyllithium are involved in this reaction. The reaction of Ph2GeMn(CO)4COMe with sodium methoxide is presumed to involve nucleophilic attack at germanium to give a methoxygermanium species. Subsequent treatment with aqueous tetraethylammonium bromide gave the hydroxygermanium complex, [cis-Ph2(HO)GeMn(CO)4C(O)Me][Et4N]. Ethylation of the same species with aqueous Et3OBF4 afforded cis-Ph2FGeMn(CO)4C(OEt)Me.

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