Formation of anionic cr-adducts from

The Formation of Anionic cr-Adducts from Heteroaromatic Compounds Structures, Rates, and Equilibria... 

Amination of 5-bromo-l,6-naphthyridine (113) gives as tele product 2-amino-l,6-naphthyridine (51 ),24 but in addition to the intermediacy of anionic cr-adduct (114) (as proved by H-NMR spectroscopy), its formation involves anionic cr-adduct 115, which is formed by a proton shift from 114. The number of atoms between positions 2 and 5 is five, thus this reaction is referred to as an odd tele substitution. Both types of tele substitution involve Addition of the nucleophile as the initial step and Elimination of the leaving group as the last step. However, in the even tele substitution the elimination can be described to take place from a neutral dihydro species, while in the odd tele substitution the elimination must occur from an anionic intermediate. In the naphthyridines several examples of even and odd tele substitutions are found, and in the following sections the results of studies concerned with tele amination are presented. 

In the negative-ion mode, galactolipids can be ionized as formation of anion adducts (i.e., [M-l-Y]- (Y = Cr, HCOQ-, -OCOCH3,. ..)). It should be recognized that as ionization conditions in the ion source become more harsh, the [M-H] ion, generated from the source fragmentation of [M-i-Y] after neutral loss of a HY molecule, becomes more intensive. Similar to their ionization in the positive-ion mode, the formation of an adduct ion depends on the concentration of the adducted anions in the matrix. An adduct anion that is preferred to use for characterization... 

Analysis of the spectrum indicated that we are dealing here with the spectrum of 4-aminodihydro-l,5-naphthyridinide (3). The results obtained by 13C-NMR spectroscopy support the formation of 3 (see Table III). From these data it is evident that the covalent amination of 1 by the amide anion is subjected to a kinetic and thermodynamic control. At low temperature ( — 40 C) the kinetically favored cr-adduct (2) is formed, and at higher temperature (10 C) the thermodynamically favored one (3) is formed. 

The 1,2-adducts (32) of 2-litho-l,3-dithians and cyclohex-2-enone can be isomerized to the more stable 1,4-adducts (33) by conversion into the potassium alkoxides (but not the less dissociated sodium or lithium salts).Direct formation of enone 1,4-adducts occurs when HMPA-THF is used as the solvent, and enolate trapping can be effected when the initial enone 1,4-adduct is treated with methyl iodide.The allylic anion derived from (34) undergoes cr-1,4-addition to cyclohexenone in the presence of Cul (Scheme 2). In the absence of the copper salt, both y-1,4- and cr-1,4-addition occur, with the former predominating. In contrast, allylation of (34) in the presence of Cul occurs primarily at the y-position, while cr-allylation is observed otherwise.The lithio-anion of 2-(yff-styryl)-... 

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