Journal ArticleDOI
Bonding Properties of Cyclopropane and Their Chemical Consequences
TLDR
The cyclopropane ring more closely resembles the CC double bond than the cyclobutane ring: it is a small ring with "double bond character" as mentioned in this paper, and while distinct differences in reactivity do exist, there are no fundamental differences in behavior.Abstract:
Among the cyclic compounds of carbon, cyclopropane and its derivatives are outstanding by virtue of their unusual structural, spectroscopic, and chemical properties. The cyclopropane ring more closely resembles the CC double bond than the cyclobutane ring: it is a small ring with “double bond character”. Cyclopropyl and vinyl groups interact with neighbouring π-electron systems and p-electron centers; both cyclopropane derivatives and olefins form metal complexes, and add strong acids, halogens, and ozone; they both undergo catalytic hydrogenation and cycloadditions. While distinct differences in reactivity do exist–the double bond usually being more reactive than the three-membered ring–there are no fundamental differences in behavior.–Although cyclopropane derivatives have been known for more than 90 years, intensive studies have been limited to the past 25 years. The development of carbene chemistry has rendered cyclopropane derivatives far more readily accessible. In recent years, the synthetic potential of the small-ring function has been increasingly exploited. A considerable number of newly developed methods utilizing this approach clearly demonstrates that the reactivity of the cyclopropene ring, like that of the CC double bond, qualify it as a “functional carbon group”. This development is in full swing; we may therefore justifiably devote considerable effort to the study of cyclopropane chemistry.read more
Citations
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Journal ArticleDOI
Stereoselective Cyclopropanation Reactions
TL;DR: This review will focus mainly on the new methods that have appeared in the literature since 1989 for stereoselective cyclopropanation reactions from olefins: the halomethylmetal-mediated cycloalkane reactions, the transition metal-catalyzed decomposition of diazo compounds, and the nucleophilic addition-ring closure sequence.
Journal ArticleDOI
If C-H bonds could talk: selective C-H bond oxidation.
TL;DR: The perspective taken herein will allow C-H oxidation reactions to be more readily incorporated into synthetic planning and to emphasize chemoselectivity imposed by the nature of the substrate.
Journal ArticleDOI
A new golden age for donor-acceptor cyclopropanes.
TL;DR: This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Journal ArticleDOI
Intrinsic Atomic Orbitals: An Unbiased Bridge between Quantum Theory and Chemical Concepts.
TL;DR: An exceptionally simple algebraic construction allows for defining atomic core and valence orbitals, polarized by the molecular environment, which can exactly represent self-consistent field wave functions, providing an unbiased and direct connection between quantum chemistry and empirical chemical concepts.
Journal ArticleDOI
Delocalization of Electrons in Molecules
TL;DR: In this article, a general method for the investigation and quantification of delocalization in molecules is proposed based on the anisotropy of the current-induced density (ACID), which is a scalar field invariant with respect to the relative orientation of the magnetic field and the molecule.
References
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Journal ArticleDOI
Methods of Reactivity Umpolung
TL;DR: There are six principal methods of umpolung: 1 2n-oxidation, heteroatom exchange and modification, homologation and its reversal, the cyclopropane “trick”, use of acetylenes, and redox reactions; under certain circumstances none of these techniques is necessary in cases where direct umpoline is possible.
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