Cyclopropane rings, cleavage

Schiller JG, AE Chung (1970) Mechanism of cyclopropane ring cleavage in cyclopropanecarboxylic acid. J Biol Chem 245 6553-6557. 

Cyclopropane ring cleavage is also observed in the case of zirconocene 2-alkene and j 2-imine complexes with adjacent cyclopropane rings to give t/3-allyl, /3-azaallyl, and t/ -enamine complexes [29]. 

DePuy, C. H. Stereochemistry and Reactivity in Cyclopropane Ring-Cleavage by Electrophiles. 40, 73-101 (1973). 

Ikegami s successful synthesis of racemic 720 materialized by initial conversion of 701 to 725 via a 1,2-carbonyl transposition sequence (Scheme LXXVIII) Treatment of 725 with methoxycarbene, deprotection, and oxidation provided 72 6. Acid-promoted cyclopropane ring cleavage and added functional group manipulation led to 727 which could be allylated stereoselectively. The tricyclic enone 724 was subsequently produced conventionally. 

Relatively few studies of the hydrogenation of substituted cyclopropanes are extant. From the studies which have been reported [26,248, 258], it would appear that, with alkyl-substituted cyclopropanes, ring cleavage occurs by rupture of the bond opposite the carbon atom carrying the greatest number of substituent groups. Thus in the platinum on... 

Nickon and Westeriuk (1967) have given an interesting analysis of 1,3-eliminations and cyclopropane ring cleavages. (These are also examples of the similarity in cyclopropanes and alkenes, with respect to... 

Since alkoxysubstituted methyl cyclopropanecarboxylates like 66 undergo ring opening upon acid treatment to provide the y-oxoester 67, the cyclopropanation/ring cleavage sequence establishes an overall nucleophilic acylation of a,(5-unsaturated esters 40). 

Other C-electrophiles besides iminium salts and carbonyl compounds have not yet extensively been tested for C-C-forming cyclopropane ring cleavage. However, whereas acyl or tertiary alkyl halides do not give addition products, benzaldimine at least provides the expected secondary amine 194 with good yield and diasteroselectivity 61). 

Delfino, A. B., and Buchs, A. Mass Spectra and Computers, 39 109-137 (1973) DePuy, C. H. Stereochemistry and Reactivity in Cyclopropane Ring-Cleavage by Electrophiles. 40, 73-101 (1973) Dimroth, K. Delocalized Phosphorus-Carbon Double Bonds. Phosphamethin-cyanines, X3-Phosphorins and 5-Phos-phorins. 38,1—150 (1973)... 

Stereochemistry and Reactivity in Cyclopropane Ring-Cleavage by Electrophiles... 

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