1- phenyl-2-methylcyclopropane

Methylcyclopropane 6 reacts selectively (> 98 %) with ZnCl2 at the less hindered site to give the homoenolate of 2-methylpropionate, whereas phenyl substituted analogue 7 is cleaved selectively (>98%) at the more substituted site [27], The latter homoenolate however suffers in situ protonation under the reaction conditions and could not be isolated. 

The reaction mixture is then heated at reflux for 3.5 hr and allowed to cool to 25°C. The benzene is removed at 25°C on a rotary evaporator to afford a dark brown oil. This was diluted with 50 mL of ether, filtered through a 3 x 14 cm column of silica gel (Note 4), and eluted with an additional 175 mL of ether. Removal of the ether under reduced pressure yields ca. 21 g of an oily orange solid that consists of a mixture of diastereomeric l-chloro-l,2-di-phenyl-3-methylcyclopropanes (Note 7). 

Spirol2-phenyl-3-methylcyclopropane-l, 9 -xanthene Typical Procedure ... 

Many cyclopropyl chlorides and bromides have been converted to alkoxycyclopropanes by treatment with a strong base, in most cases potassium rerf-butoxide, in an appropriate organic solvent (Table 13). Under such conditions, hydrogen halide elimination takes place, yielding strained cyclopropene intermediates, which are trapped by nucleophilic attack of the alkoxide. Overall, a simple substitution occurs when a bond is formed between the alkoxide group and the carbon atom to which the halide was attached. This is the case when l-chloro-5-methyl-exo-6-phenyl-3-oxabicyclo[3.1.0]hexan-2-one (1) was reacted with potassium /ert-butoxide l-/er/-butoxy-5-methyl-ent/o-6-phenyl-3-oxabicyclo[3.1.0]hexan-2-one (2) was isolated in 94% yield.If a C-O bond is established at the other olefinic carbon atom, a C H bond is concomitantly formed at the carbon atom, to which the halide was attached. The result is a double substitution which is discussed elsewhere (see Section 5.2.1.3 ). When the substrate contains more than one halogen atom, several elimination reactions usually take place. Thus, treatment of 1 -bromo-2-chloro-2-methylcyclopropane (3) with an excess of potassium /er/-butoxide gave l-ter/-butoxy-2-methylenecyclopropane (4) in 30% yield. 

Reactions of this type result in formation of 1,1-dihalocyclopropanes. Such compounds are available by a large number of alternative routes, and this may explain why only a couple of such syntheses have been reported. The most efficient process converts 2-aryl-1,1-dichloro-2-methylcyclopropanes into the corresponding 3-aryl-l, 1,2,2-tetrachloro-3-trichloromethylcyclo-propanes, which is achieved by chlorine treatment. " When the reaction was carried out with l,l-dichloro-2-methyl-2-phenylcyclopropane, l,l,2,2-tetrachloro-3-phenyl-3-trichloromethyl-cyclopropane (1) was obtained in essentially quantitative yield. ... 

Most alkylidenecyclopropanes have been prepared by reacting cyclopropylidenetriphenyl-.i -phosphane with aldehydes and ketones. The phosphorus ylide is either prepared by treating cyclopropyltriphenylphosphonium bromide, a stable compound, with base, e.g. phenyl-lithium, potassium er/-butoxide, sodium hydride, or by generating both the phos-phonium salt and the ylide in situ from (3-bromopropyl)triphenylphosphonium bromide employing two equivalents of base. ° The latter method seems to give somewhat better yields, as indicated by the synthesis of l-diphenylmethylene-2-methylcyclopropane (1) from ben-zophenone. ° The yield has also been increased by adding a catalyst. Considerable improvements have in particular been observed by using tris[2-(2-methoxyethoxy)ethyl]amine, a phase-transfer catalyst, e.g. formation of The use of several phosphorus ylides and bases is summarized in Table 25. 

If other reactive moieties are present a cyclopropanecarbonyl compound can be converted to the corresponding cyclopropylalkane using various conditions. Thus, 3,4-benzotricy-clo[4.3.1.0 ]dec-3-en-2-one yielded 3,4-benzotricyclo[4.3.1.0 ]dec-3-ene in excellent yield on treatment with sodium in liquid ammonia. di-l-Methylcyclopropane-l,2-dicarboxylic anhydride underwent a similar reaction to afford isomeric lactones on treatment with lithium aluminum hydride or sodium borohydride in tetrahydrofuran. On the other hand, ionic hydrogenation (triethylsilane in trifluoroacetic acid and water) of cyclopropyl phenyl ketone gave a complex reaction mixture and very little benzylcyclopropane. ... 

In the case of sMMO from M. trichosporium OB3b, it has been found that the ring-opened products are produced by the reaction of fra 5-l-phenyl-2-methylcyclopropane as shown in eq. (20) [77]. The radical mechanism accounts for the formation of the ring-opened product in this reaction. The oxygenation mechanism for this sMMO may be different from that for sMMO from M. capsulatus (Bath). 

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