Ground-and excited-state tautomerism in porphycenes
Article Abstract:
A different display of tautomeric properties in porphycenes than their constitutional isomers, porphyrins, is attributed to the short distances between the inner nitrogen atoms and therefore, strong intramolecular hydrogen bonds. It is demonstrated that the excited-state process is gated by a low-frequency vibration that simultaneously strengthens both hydrogen bonds by bringing the hydrogen donor and acceptor atoms closer together and making the hydrogen bonds more linear, for porphycene in condensed phases.
Publication Name: Accounts of Chemical Research
Subject: Science and technology
ISSN: 0001-4842
Year: 2006
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Search for solutions to the reactivity and selectivity problems in enyne metathesis
Article Abstract:
Enyne metathesis is a powerful carbon-carbon bond-forming reaction to generate 1,3-dienes from an alkyne and an alkene, but it suffers from both region- and stereoselectivity problems. A study describes the evolution of various new strategies and substrate platforms to address the reactivity and selectivity issues in the enyne metathesis processes.
Publication Name: Accounts of Chemical Research
Subject: Science and technology
ISSN: 0001-4842
Year: 2006
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Enantiomerically enriched allylic alcohols and allylic amines via C-C bond-forming hydrogenation: asymmetric carbonyl and imine vinylation
Article Abstract:
Hydrogenation of alkynes in the presence of carbonyl compounds and imines applying cationic rhodium(I) and iridium(I) precatalysts enables the formation of allylic alcohols and allylic amines. Hydrogenative fragment couplings circumvent the use of preformed organometallic reagents and avoid the generation of stoichiometric byproducts.
Publication Name: Accounts of Chemical Research
Subject: Science and technology
ISSN: 0001-4842
Year: 2007
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