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Lithium acetylenic

The addition of lithium acetylene 184 (obtained from Z-methoxybut-l-en-3-yne) to 5-valerolactones at -78°C in THF gives the ketoalcohol 188 (83TL5303 90JOC5894). The conversion of the latter to spiroketal 189 is accomplished under the action of 30% perchloric acid in methylene chloride, yield 58% (90JOC5894). [Pg.206]

Ethynyl compounds react with sugar lactones to give acetylenic lactols (16,63). Reaction of 2,3-O-isopropylidene-D-ribonolactone (16a) with lithium acetylenic derivatives gave l-(2-substituted ethynyl)-2,3-0-isopropyli-dene-D-ribofuranoses. Similarly, treatment of 2,3 5,6-di-O-isopropylidene-L-gulono-1,4-lactone (9b) with various lithium acetylenic reagents gave... [Pg.139]

Unfortunately, the only available theoretical study on lithium-acetylene species is that of Apeloig and coworkers on dilithioethylene, in which the most stable isomer of Li2C2H2 was found to have a C2v geometry with two lithium atoms bridging the C—C bond and the C2H2 group in a cis planar position. This seems to indicate structure 5 more probable than structure 4. Consequently, the structure, which meets best all conditions, is 5 (Scheme 3). ... [Pg.238]

CHj) and several oxa- and ihia-derivatives (X - O, S). In this case, the preferred direction of attack is usually A, regardless of the substituent s position, type of amino group, and homo- or heterocyclic ring, the only exceptions being those of the lithium-acetylene reagent with dimethylaminomethyl cyclohexanone derivatives. [Pg.205]

In strict correlation with the early method for the preparation of symmetrical diaryl tellurides by treatment of tellurium(IV) halides with 4 mol equiv of aryl Grignard reagent (see Section 3.1.2.4), dialkynyl tellurides are prepared starting from bromomagnesium and lithium acetylenic derivatives. ... [Pg.110]

SULFUROUS OXIDE (7446-09-5) SO, Noncombustible liquefied gas under pressure or liquid. Contact with air forms hydrogen chloride fumes. Violent reaction with water or steam, forming sulfurous acid, a medium-strong acid and corrosion hazard. Reacts violently with acetylene, acrolein, alcohols, aluminum powder alkali metals (i.e., potassium, sodium) amines, ammonia, bromine pentafluoride butadiene caustics, cesium acetylene carbide chlorates, chlorine trifluoride chromium powder copper or copper alloy powders chlorine, diethylzinc, fluorine, ethylene oxide lead dioxide lithium acetylene carbide diamino-, metal powders monolithium acetylide-ammonia nitryl chloride potassium acetylene carbide potassium acetylide, potassium chlorate rubidium carbide silver azide sodium acetylide staimous oxide. Decon oses in... [Pg.981]


See other pages where Lithium acetylenic is mentioned: [Pg.110]    [Pg.389]    [Pg.389]    [Pg.74]    [Pg.55]    [Pg.976]    [Pg.981]    [Pg.982]    [Pg.190]    [Pg.475]    [Pg.561]    [Pg.1105]    [Pg.1110]    [Pg.1111]    [Pg.1111]    [Pg.1111]   
See also in sourсe #XX -- [ Pg.110 ]




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