Arylcyclopropanes Phenylcyclopropanes

Nucleophiles also add to radical cations of arylcyclopropanes to give anti-Markownikoff-type adducts [40-43]. There are two possible structures for the radical cations of arylcyclopropanes i.e., ring opened 1,3-radical cation and ring closed cyclopropane radical cation. Dinnocenzo reported that the photoinduced electron transfer reaction of chiral trans-l-methyl-2-phenylcyclopropane in methanol gives chiral 3-methoxy-l-phenylbutane via the radical cation [44], This result indicates that the radical cation in the ring closed form is attacked by methanol. The fact that this cyclopropane does not isomerize under the photochemical reaction conditions supports this conclusion (Scheme 11). 

Arylcyclopropanes can be prepared from a variety of alkenes enamines react sluggishly, electron-rich alkenes are, in general, the most reactive. Thus, phenylcarbene, generated by dirhodium tetraacetate catalyzed decomposition of phenyldiazomethane, gave 2-butyl-1-phenyl-cyclopropane (2) in 6% yield from hex-l-ene, but l-butoxy-2-phenylcyclopropane (3) was obtained in 92% yield from butyl vinyl ether. ... 

Various arylcyclopropanes have been synthesized by heating mixtures of cyclopropyllithium, obtained from bromocyclopropane and lithium, and a halobenzene or a nitrogen-containing aromatic heterocycle. The cleanest reactions and the best yields are afforded when heterocyclic reactants are employed. Thus, reflux of an ethereal solution of cyclopropyllithium and fluorobenzene gave mainly phenylcyclopropane (1) and 2-cyclopropylbiphenyl (2), which were isolated in 37 and 25% yield, respectively. If the aromatic compound was pyridine, the analogous substitution product, 2-cyclopropylpyridine (3), was obtained in 58% yield. ... 

Cyclopropane bonds are susceptible to oxidative cleavage (see Section 2.1.1.2.). Most of the oxidation reactions of activated cyclopropanes involve phenyl-substituted derivatives. When phenylcyclopropane was treated with lead(IV) acetate, 1,3-diacetoxy-l-phenylpropane (63%) and the elimination product cinnamyl acetate (32%) were obtained. The occurrence of traces of l,3-diacetoxy-2-phenylpropane could not be confirmed in later studies. The kinetics of the oxidation of various arylcyclopropanes with lead(IV) acetate, thallium(III) acetate and mercury(II) acetate have been studied. 4-Methoxyphenyl, 4-tolyl, and 4-chlorophenyl derivatives and their meta analogs were treated with these reagents and the rates of reaction and product distributions analyzed. Using lead(IV) acetate, diacetates 1 and cinnamyl acetates 2 were obtained in ratios of about 4 1, whereas thalhum(III) acetate gave the diacetates almost exclusively (see following table). ... 

Studies on the nitration and bromination of arylcyclopropanes have continued/ and for the latter process 1-phenylcyclopropane in chloroform affords up to 20% of product retaining the three-membered ring. Bromination of dipropylcyclopropenone (184 = Pr) with molecular bromine effects ring cleavage to give (185)... 

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