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2005
Pyrazine derivatives
R 0550
Mono- and Diadducts and Bicyclic Adducts in Reactions of 2,3-DicyanoCation with C- and O-Nucleophiles. — The reactivity of
09- 159 -1-ethylpyrazinium
pyrazinium salt (III) towards O-nucleophiles (IV) and (XI), C-nucleophiles
(VIa)—(VIc), and C,O-dinucleophiles, e.g. (IX), is investigated. Diadducts of O- and
C-nucleophiles to the cation of (III) are isolated for the first time. For example, the high
reactivity of the cation enables the preparation of diadducts not only with primary
alcohols (IVa) and (IVb) but also with secondary alcohol (IVc). Tandem AN—AN reactions of (III) with enolates, e.g. (IX), or keto esters afford tetrahydrofuropyrazines such
as (X), whereas reaction of (III) with ethylene glycol (XI) proceeds as successive
addition of the alcoholic fragments to the unsubstituted C-atoms of the heterocycle.
Due to its instability, one of the alkoxy groups in (V) is replaced with a C-nucleophilic
fragment to give mixed C,O-diadducts (VII). — (SLEPUKHIN*, P. A.; RUSINOV, G.
L.; CHARUSHIN, V. N.; FILYAKOVA, V. I.; KARPENKO, N. S.; KRIVOLAPOV, D.
B.; LITVINOV, I. A.; Russ. Chem. Bull. 53 (2004) 6, 1272-1278; Inst. Org. Synth.,
Ural Div. Russ. Acad. Sci., Ekaterinburg 620219, Russia; Eng.) — H. Hoennerscheid
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