Trans-1 -phenyl-2-methyl-cyclopropane

Crawford and Hutson (1977) studied the metabolism of a 1.5 mg/kg oral dose of benzyl- " C-labeled fenpropathrin in the rat. The stereochemistry of fenpropathrin was not indicated. Fifty-seven percent of the administered dose was eliminated in urine and 40% in feces within 48 h. Fenpropathrin was hydroxylated on the phenyl ring to form 4 -OH fenpropathrin and at a trans methyl group on the cyclopropane ring. The intact hydroxylated esters and fenpropathrin were cleaved by carboxylesterase action and eliminated as the glucuronide of tetramethyl CPCA (2, 2, 3, 3-tetramethyl cyclopropanecarboxylic acid CAS no. 15641-58-4), 2-OH, trimethyl CPCA (2-(hydroxymethyl)-2, 3, 3-trimethyl-cyclopropanecarboxylic acid CAS no. 97280-65-4), and the O-sulfates of the oxidized 3-phenoxybenzene moiety. 

It is assumed that the reaction proceeds by the oxidative addition of the carbon-carbon bond of the cyclopropane to cobalt species to form a metallacyclic intermediate. The regioselectivity of this reaction is controlled by the relative ease of insertion of the cobalt species into the C1-C2 and the C1-C3 bonds of the cyclopropane (Scheme 7). In the case of the reaction of the (1-R, 2k )-isomer trans-l5a, 5-methyl-3-phenyl-2-cyclopenten-1-one (17a) is produced via TS2 without any serious steric repulsion, while the 4-methyl isomer 16a must be pro-... 

Other reversible ET-catalyzed stereoisomerizations of cyclopropanes have been observed with cjs-l-methyl-2-phenyl-, r-1-phenyl-l-methyl-c-2-methyl- and optically active l-methyl-2,2-diphenylcyclopropane (190, 191 and ( + )-(/ )-49, respectively) . Experimental evidence for the existence of intermediate cyclopropane radical anions like CIS- or trans-llH" (Scheme 18) has not been found in the course of these investigations. 

The addition of phenyllithium to cyclopropene occurred with 99% stereoselectivity to give cw-l-lithio-2-phenylcyclopropane, albeit in 3 /o yield. With 3-methylcyclopropene, the reaction was more efficient and, after protonation of the lithiocyclopropane, 2-methyl-1-phenyl-cyclopropane was obtained in 44.5% yield. The product is about 94% in the trans form thus attack of the organolithium occurs on the opposite face to that bearing the larger substituent at C3. When the cyclopropene is 3,3-disubstituted, e.g. 17, both faces are sufficiently hindered to slow the addition process and metalation of a vinylic hydrogen predominates. ... 

The fate of diazirines on decomposition can be influenced by the addition of y -cyclodextrin (j6-CD). When 3-methyl-3-phenyl-3jf/-diazirine (3) was thermolyzed under argon, 1 -methyl-1,2-diphenylcyclopropane (4) was obtained as an isomeric mixture in close to 20% yield the main product (43% yield) was acetophenone azine (5). Cyclodextrin complexation prior to pyrolysis, however, increased the yield of 4 tremendously. The carbohydrate, therefore, facilitates both styrene (6) and cyclopropane formation.It is also interesting to note that the trans-41 cis-4 ratio increased concomitantly and that styrene appears as an isolable product after photochemical, but not after thermal degradation of the 3 /(-CD complex. 

Although pyrolysis of several phenyl-substituted cyclopropanes results in extrusion of phenyl-carbene, which undergoes addition to C-C double bonds and forms phenylcyclopropanes under the experimental conditions employed, the overall efficiency of the process is generally too low to make it an attractive method for synthesis on a preparative scale. Thus, phenylcarbene, generated by photolysis of trans-l,2-diphenylcyclopropane or 1,2,3-triphenylcyclo-propane, forms 2-ethyl-2-methyl-1-phenylcyclopropane in only 6% yield as a mixture of isomers when the reaetions are carried out in 2-methylbut-l-ene. ... 

AI3-29062 Anchimanaito 20S Anvil Anvil 2 2 ULV Anvil 10 10 ULV Benzyl alcohol, m-phenoxy-, 2,2-dimethyl-3-(2-methylpropenyl)cyclopropanxxboxylate Caswell No. 652B CCRIS 2602 Cyclopropanecarboxylic xid, 2,2-dimethyl-3-(2-methyl-1-propenyl)-, 3-(phenoxy-phenyl)methyl ester, cis,trans-( )- Cyclopropane-carboxylic acid, 2,2-dimethyl-3-(2-methyl-1-propenyl)-,... 

Later Olah et al. showed that the trans-chloride 605 with SbFj—SO Fl yield a 3-cyclohexenyl cation 606, but not the ion 520 thus, just as under solvolytk conditions, ion 520 is formed only when cr-participation is possible in the transition state of ionisation. In the same paper it was pointed out that ion 520 could be generated from the alcohol if freshly distilled SbFj in SOjFQ (—78 "C) was used the admixtures of proton acids, the authors maintain, favour the opening of the cyclopropane ring before ionization. The ionization of 3-methyl- 607 and 3-phenyl-cis-bicyclo[3,l,0]hexanol-3 608 in SbFj—SOjFCl results in the 3-methyl-cyclo-hexenyl ion 609 and the 3-methyl-l-phenylcyclopentenyl ion 610. That the ionization of tertiary substrates results in classical tertiary carbocations rather than trishomocyclopropenyl ions appears to be due to the hindrance in passing from the conformation of the bath to the chair which is indispensable for the formation of a delocalized ion. 

Ri = R2 = Ph, R3 = Me, R4 = H) with methyl diazoacetate in dichloromethane. With styrene, a diastereoselectivity in favour of the trans cyclopropane with a predominance of C over D was observed (C/B 71/29, C 91% ee B 87% ee) with a yield of 69% (Scheme 36). Compared to the non-supported catalytic system (ligand 75b), the results in terms of diastereoselection and ee were 10% lower. The possibility of the reuse of this catalytic system was examined. 13 cycles were conducted without loss of ee, but to keep a good yield after the 10 use, it was necessary to reactivate the catalytic system with phenyl hydrazine. 

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