Alkenes s. Ethylene derivatives

Alkenes s. Ethylene derivatives Alkoxides s. Alkali alkoxides Alkoximes... 

Alkali met hydrides, superactive -, reactions with - 43, 34 Alkali metal selenides -, in s/tu-preparation 43, 529 Alkene oxides s. Oxido compds. Alkenes s. Ethylene derivs. 

Alkenes s. Ethylene derivatives Alkenynes s. Enynes Alkoxides (s. a. Alkali... 

Alkene oxides s. Oxido compds. Alkenes s. Ethylene derivs. Alkenylidenecyclopropanes... 

Reaction of 2-chloromethyl-4//-pyrido[l,2-u]pyrimidine-4-one 162 with various nitronate anions (4 equiv) under phase-transfer conditions with BU4NOH in H2O and CH2CI2 under photo-stimulation gave 2-ethylenic derivatives 164 (01H(55)535). These alkenes 164 were formed by single electron transfer C-alkylation and base-promoted HNO2 elimination from 163. When the ethylenic derivative 164 (R = R ) was unsymmetrical, only the E isomer was isolated. Compound 162 was treated with S-nucleophiles (sodium salt of benzyl mercaptan and benzenesulfinic acid) and the lithium salt of 4-hydroxycoumarin to give compounds 165-167, respectively. 

Five-membered ring closure has also been observed upon Pd-catalyzed coupling of o-halostyrene derivatives with alkenes. Apparently, an intramolecular carbopaUadation with 5-exo-trig ring closure can favorably compete with /S-hydride elimination in the intermediate j8-(o-ethenylphenyl)ethylpalladium halide. This reaction mode for the alostyrene is observed especiaUy under Jeffery conditions when the alkene is ethylene, propene, or an... 

Nenajdenko et al. described the first example of addition of a 1,2-dication to C-C mutiple bonds. The only S-S dication found to participate in this reaction was the highly strained dication 115 derived from 1,4-dithiane. The reaction with alkenes 119 proceeded under mild conditions and led to derivatives of dithioniabicyclo[2.2.2]octane 120 as shown in Equation (33) and Table 21 <1998JOC2168>. This reaction was sensitive to steric factors and proceeded only with mono and 1,2-disubstituted ethylenes. Only alkenes conjugated with aromatic or cyclopropane moieties underwent this reaction. For the 1,2-disubstituted alkenes used in this study, the relative configuration of substitutents at the double bond was preserved and only one diastereomer was formed (see entries 2 and 3). 

Dtatmno-l-alkenes. Doss Bost (Ref 1) describe the prepn of 1, 2-bis(dimethyl-amino) ethylene (bp 38-40° at 15mm l, s 4648), its hydrogenation in a Parr bomb at 40lb/sq inch to the ethane (nfi 1.4170) and the use of the ethane deriv as a component of hypergolic fast-burning rocket fuels... 

There appears to be some discrepancy in the literature as to the reasons for the instability of [Mn(C2H.s)(CO)5] and, presumably, [Mn(n-C3H7)(C0)5]. Several reports attribute the instability to a very facile /3-hydride transfer/alkene elimination process (1,34,43,44). Thus, the observation that [Mn(CH2SiMe3)(CO)5] is more stable than [Mn(C2Hj)(CO)5] was attributed to the lack of /3-hydrogens in the former complex (45). However, a )8-elimination reaction from [Mn(C2H5)(C05] would be expected to result in the formation of ethylene and [Mn(H)(CO)s] (which could decompose to [Mn2(CO)io]). However, neither ethylene nor [Mn(H)(CO)5] have been observed in the decomposition of [Mn(C2H5)(CO)s]. Propionyl manganesepentacarbonyl and [Mn2(CO)io] (which could derive from any source of [Mn(R)(CO)5]) are the observed decomposition products (12,16,37,46). 

Use for resolution of cycloalkenes. W s-Cycloalkenes of intermediate size (Cg-Cjo) should be capable of existing in enantiomeric forms because of the inability of the trans double bond to rotate with respect to the remainder of the molecule. But in the absence of salt-forming groups, resolution cannot be accomplished by the usual methods of forming derivatives. However, Cope et al.s found that the strong tendency of an alkene to complex with a platinum compound provides an effective method of resolution. The complex of ethylene with platinous chloride and (+) or (-)-a-methylbenzylamine exists in only one form since ethylene is symmetrical. But addition of the base to a solution of the platinum complex of trans-cyclooctene opens the way for formation of the diastereoisomeric complexes derived from the R- and S-forms of the base. Fractional crystallization at —20° (liquid at 25°) effected separation. Liberation of the (—)-hydrocarbon from the complex with potassium cyanide gave a product of aD — 411°. 

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