Cyclopropanes from unsaturated compounds

H. E. Simmons, T. L. Caims, S. A. Vladuchick, and C. M. Hoiness, Cyclopropanes from Unsaturated Compounds, Methylene Iodide, and Zinc-Copper... 

Cyclopropanes from unsaturaled carbonyl compounds via pyraaolines by catalytic pyrolysis... 

In analogy to the cycloaddition of electron-rich alkenes with electron-deficient olefins , cycloadditions between donor-acceptor pairs of cyclopropanes and unsaturated compounds have been obtained. They include for instance the cycloaddition of substituted cyclopropanes with ethylene-tetracarbonitrile (TCNE), (equation 23 ). [10]Paracyclophadienes have been obtained from the reaction of tetrasubstituted 1,2-dicyclopropylethylenes with TCNQ. ... 

Intramolecular carbenoid reactions of diazo compounds have been limited to the formation of only a few silicon-substituted cyclopropanes from unsaturated silicon-substituted diazo compounds. 

Much of the early work into the rhodium(II)-catalysed formation of oxazoles from diazocarbonyl compounds was pioneered by the group of Helquist. They first reported, in 1986, the rhodium(II) acetate catalysed reaction of dimethyl diazomalonate with nitriles.<86TL5559, 93T5445, 960S(74)229> A range of nitriles was screened, including aromatic, alkyl and vinyl derivatives with unsaturated nitriles, cyclopropanation was found to be a competing reaction (Table 3). 

Synthesis of a-alkoxyketones from a-diazocarbonyl compounds and alcohols under the influence of copper or rhodium catalysts is well established as an alternative to the Lewis or proton acid catalyzed variant of this synthetic transformation. The sole recent contribution to the aspect of general reactivity deals with the competition between O/H insertion and cyclopropanation of unsaturated alcohols 162). The results... 

The Simmons-Smith reaction is an efficient and powerful method for synthesizing cyclopropanes from alkenes [43]. Allylic alcohols are reactive and widely used as substrates, whereas a,j8-unsaturated carbonyl compounds are unreactive. In 1988, Ambler and Davies [44] reported the electrophilic addition of methylene to a,/3-unsaturated acyl ligands attached to the chiral-at-metal iron complex. The reaction of the racemic iron complex 60 with diethylzinc and diiodomethane in the presence of ZnCl2 afforded the c/s-cyclopropane derivatives 61a and 61b in 93 % yield in 24 1 ratio (Sch. 24). 

From these results, it is concluded that, after exchange with Ca2+, zejolite LTA can selectively adsorb n-butanol and higher normal alcohols, n-butene and higher normal alkenes, propane and C4 Ci4 normal alkanes, and cyclopropane, etc., which cannot be adsorbed by zeolite 4A. On the other hand, the presence of divalent Ca2+ promotes the adsorption selectivity of 5A zeolite for polar molecules and other unsaturated compounds. 

Details have appeared of the formation of cyclopropanes from arylidene-malononitriles and the biacetyl-trimethyl phosphite adduct. 1,2-Oxaphospholens.— Among a 3-unsaturated ketones used in the formation of 1 1 adducts with tervalent phosphorus compounds are the sulphone (42) ... 

T his work concerns the study of the polymerization of cyclopropane, substituted cyclopropanes, and conjugated cyclopropanes in the presence of cationic and Ziegler-Natta polymerization. The unsaturation of cyclopropane has been described by several workers in the same way as unsaturated compounds. The unsaturation of cyclopropane compounds, which is the basis for the polymerization of these structures, can be explained by the electronic repartition on the three carbon atoms of the ring. Determination of the dipolar moment of chlorocyclopropane has shown that the carbonium ion resulting from the attack of the ring by a carbo cation is stabilized in a homoallylic structure. 

Cyclopropanes from aj unsaturated carbonyl compounds. This new transformation is illustrated for conversion of cinnamaldehyde into phenylcyclopropane (equation I). The sequence involves Michael addition of sodium thiophenoxide... 

The discussed reactions of carbene and carbyne complexes show that they have essential significance as catalysts or unstable transient intermediate compounds in such catalytic processes as metathesis of olefins and other unsaturated compounds, Fischer-Tropsch synthesis, syntheses of cyclopropanes from diazoalkanes and olefins, and polymerization of olefins and alkynes as well as in organic synthesis. Except for alkynes [reaction (5.132) ] some compounds containing double bonds react with carbon monoxide and carbene ligands to form bonds with those groups. Examples of such compounds are enamines, ynamines, and Schiff bases. The JV-vinylpyrrolidone (enamine), methoxyphenylcarbene, and excess of CO (higher pressure) react to furnish enaminoketone. 

Reactions with a,jS-Unsaturated Compounds. If the carbonyl is a, -unsaturated, reaction takes place at the alkene via addition/substitution to form em-dimethyl-substituted cyciopropanes. For example, the em-disubstituted cyclopropane was prepared from cyclohexenone in 74% yield (eq 6). ... 

The synthesis of cyclopropanes from a,jS-unsaturated carbonyl compounds, involving bond formation between the /8-carbon and the carbonyl carbon centres, has been accomplished in an interesting manner involving electrochemical reduction of the intermediate mesylate (15) as a key stage (Scheme 4). ... 

Epoxidation of aldehydes and ketones is the most profound utility of the Corey-Chaykovsky reaction. As noted in section 1.1.1, for an a,P-unsaturated carbonyl compound, 1 adds preferentially to the olefin to provide the cyclopropane derivative. On the other hand, the more reactive 2 generally undergoes the methylene transfer to the carbonyl, giving rise to the corresponding epoxide. For instance, treatment of P-ionone (26) with 2, derived from trimethylsulfonium chloride and NaOH in the presence of a phase-transfer catalyst Et4BnNCl, gave rise to vinyl epoxide 27 exclusively. ... 

Cyclopropanes 93 are obtained in satisfactory yields from both a,p-unsaturated carbonyl compounds and nitriles, when these substrates are allowed to react with... 

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