22467-91-0Relevant articles and documents
Diastereoselective synthesis of bicyclopropanes
Theberge, Cory R.,Zercher, Charles K.
, p. 9181 - 9184 (1994)
Diastereoselective cyclopropanation of a trans-substituted vinyl cyclopropane was studied. The stereochemistry of the major and minor isomers was assigned by diastereoselective synthesis of the two isomers.
Copper-mediated oxidative transformation of N-allyl enamine carboxylates toward synthesis of azaheterocycles
Toh, Kah Kah,Biswas, Anup,Wang, Yi-Feng,Tan, Yun Yun,Chiba, Shunsuke
, p. 6011 - 6020 (2014/05/20)
A method for synthesis of 3-azabicyclo[3.1.0]hex-2-enes has been developed by intramolecular cyclopropanation of readily available N-allyl enamine carboxylates. Two complementary reaction conditions, CuBr-mediated aerobic and CuBr2-catalyzed-PhIO2-mediated systems effectively induced stepwise cyclopropanation via carbocupration of alkenes. Oxidative cyclopropane ring-opening of 5-substituted 3-azabicyclo[3.1.0]hex-2-enes was also developed for synthesis of highly substituted pyridines. In addition, diastereoselective reduction of 3-azabicyclo[3.1.0]hex-2-enes to 3-azabicyclo[3.1.0]hexanes was achieved using NaBH3CN in the presence of acetic acid.
Vinylcyclopropylacyl and polyeneacyl radicals. Intramolecular ketene alkyl radical additions in ring synthesis
De Boeck, Benoit,Herbert, Nicola M. A.,Harrington-Frost, Nicole M.,Pattenden, Gerald
, p. 328 - 339 (2007/10/03)
Treatment of a variety of substituted vinylcyclopropyl selenyl esters, e.g. 11, with Bu3SnH-AIBN in refluxing benzene leads to the corresponding acyl radical intermediates, which undergo rearrangement and intramolecular cyclisations via their ketene alkyl radical equivalents producing cyclohexenones in 50-60% yield. By contrast, treatment of conjugated triene selenyl esters, e.g. 32, with Bu3SnH-AIBN produces substituted 2-cyclopentenones via intramolecular cyclisations of their ketene alkyl radical intermediates. Under the same radical-initiating conditions the selenyl esters derived from o-vinylbenzoic acid and o-vinylcinnamic acid undergo intramolecular cyclisations producing 1-indanone and 5,6-dihydrobenzocyclohepten-7-one respectively in 60-70% yields. A tandem radical cyclisation from the α,β,γ, δ-diene selenyl ester 31 provides an expeditious synthesis of the diquinane 35 in 69% yield.
Vinylcyclopropylacyl Radicals. Intramolecular Ketene Additions leading to Concise Syntheses of Cyclohexenones
Herbert, Nicola,Pattenden, Gerald
, p. 69 - 70 (2007/10/03)
Treatment of a range of vinylcyclopropyl selenyl esters with Bu3SnH-AIBN produces cyclohexenone products (50-60%) via 6-exo-dig radical cyclisations involving ketene intermediates.
Regioselective Ring Opening of Vinylcyclopropanes by Hydrogenation with Palladium on Activated Carbon
Barrett, Anthony G. M.,Tam, William
, p. 7673 - 7678 (2007/10/03)
A highly regioselective reductive ring opening of vinylcyclopropanes induced by palladium on activated carbon has been investigated. High yields and excellent regioselectivities were observed in cleaving either the less hindered bond or the more hindered bond of the cyclopropane depending on whether the substituent on the vinylcyclopropane is capable of coordinating to Pd or not.
Studies on the diastereoselective preparation of bis-cyclopropanes
Theberge, Cory R.,Verbicky, Christopher A.,Zercher, Charles K.
, p. 8792 - 8798 (2007/10/03)
The identification of two natural products, FR-900848 and U-106305, has stimulated interest concerning the relationship between configurational isomerism, conformational isomerism, and biological activity of polycyclopropanes. Efforts to investigate the relationship between configurational and conformational isomerism through molecular modeling suggest that significantly different three-dimensional structures will result from unique primary structures. Any effort to address these issues demands that stereoselective methods for the preparation of polycyclopropanes be developed. We have investigated the application of zinc-carbenoid cyclopropanation in the presence of chiral dioxaboralanes to the preparation of eight stereochemically unique bicyclopropanes. The frans-vinylcyclopropane starting materials demonstrated very little substrate-induced stereoselectivity, while the cis-vinylcyclopropane demonstrates modest to excellent stereocontrol. A model for the substrate-based stereocontrol is proposed. We also used the spectroscopic data gathered in this investigation to probe the substrate-mediated stereocontrol in the rhodium(II)-catalyzed cyclopropanation of vinylcyclopropanes with ethyl diazoacetate.
