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- Publications
- Influence
A new catalytic hetero-Heck type reaction.
- Juho Helaja, R. Goettlich
- Medicine, Chemistry
- Chemical communications
- 21 March 2002
Unsaturated N-chloroamines have been found to cyclise under palladium-catalysis in good yield, the proposed mechanism includes an oxidative addition of the chloroamine to Pd(0), thus opening a new… Expand
Noncovalent attachment of pyro-pheophorbide a to a carbon nanotube.
- Jari S. Kavakka, S. Heikkinen, I. Kilpeläinen, M. Mattila, H. Lipsanen, Juho Helaja
- Chemistry, Medicine
- Chemical communications
- 24 January 2007
Pyrene mediated noncovalent attachment of a chlorophyll derivative, pyro-pheophorbide a, to a soluble single wall carbon nanotube is reported and the resultant CD, UV-Vis absorbance, fluorescence and… Expand
Gold‐Catalyzed Conversion of Aryl‐ and Alkyl‐Substituted 1‐(o‐Aminophenyl)‐2‐propyn‐1‐ones to the Corresponding 2‐Substituted 4‐Quinolones
- Otto Seppänen, Mikko Muuronen, Juho Helaja
- Chemistry
- 1 July 2014
Gold-catalyzed cyclization of alkyl- or aryl-substituted 1-(o-aminophenyl)-2-propyn-1-ones to the corresponding 2-substituted 4-quinolones was studied with various gold salts and complexes. Screening… Expand
E-Ring extended estrone derivatives: introduction of 2-phenylcyclopentenone to the estrone D-ring via an intermolecular Pauson-Khand reaction
- Emmi Kaasalainen, J. Tois, L. Russo, K. Rissanen, Juho Helaja
- Chemistry
- 7 August 2006
Abstract An expedient synthetic route to E-ring extended estrone derivatives is reported. Estrone-derived cyclopentenones were accessed by an intermolecular Pauson–Khand (PK) cycloaddition. It was… Expand
Intermolecular oxidative dehydrogenative 3,3′-coupling of benzo[b]furans and benzo[b]thiophenes promoted by DDQ/H+: total synthesis of shandougenine B
- Tom Wirtanen, Mikko Muuronen, Juha Hurmalainen, H. Tuononen, M. Nieger, Juho Helaja
- Chemistry
- 14 November 2016
With an excess of a strong acid, 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ) is shown to promote metal-free intermolecular oxidative dehydrogenative (ODH) 3,3′-coupling of 2-aryl-benzo[b]furans and… Expand
CHLOROPHYLLS. VIII. SYNTHESIS OF A NEW CHLOROPHYLL DERIVATIVE AND ANTHRAQUINONE-BASED DYAD AND TRIAD MOLECULES FOR EXECUTING PHOTOINDUCED ELECTRON TRA NSFER
- A. Tauber, Juho Helaja, +7 authors B. Wood
- Chemistry
- 1997
Zn Pyropheophorbide a : A β-Face Selective Nicotine Receptor
- Jari S. Kavakka, S. Heikkinen, Juho Helaja
- Chemistry
- 1 October 2008
Nicotine binds to a semisynthetic chlorophyll a derivative, Zn pyropheophorbide a, in a receptor-like manner to form a 1:1 complex with β-face diastereomeric configuration. The geometry of the… Expand
Complete assignment of the 1H and 13C NMR spectra and conformational analysis of bonellin dimethyl ester
- P. Hynninen, Juho Helaja, Franz-Peter Montforts, C. Müller
- Chemistry
- 1 December 2004
The use of a high-field NMR instrument (ν(1H) = 500 MHz) and 2-dimensional NMR techniques (HMQC, HMBC, ROESY) enabled us to fully assign the 1H and 13C chemical shifts of bonellin dimethyl ester. The… Expand
Gold(I)-catalyzed 1,3-O-transposition of ynones: Mechanism and catalytic acceleration with electron rich aldehydes
- Santeri Aikonen, Mikko Muuronen, +4 authors Juho Helaja
- Chemistry
- 5 January 2018
The gold-catalyzed 1,3-O-transposition of ynones occurs intermolecularly via a cyclic organo-gold acetal intermediate formed from the nucleophilic oxo attack of a second ynone, i.e. either starting… Expand
Development of Dpa-based imidazole zinc anion receptors
- T. M. Salo, Juho Helaja, A. Koskinen
- Chemistry
- 24 April 2006
Abstract A synthetic route for a new, phenolic Dpa-based aza ligand is presented and its chelation with zinc ions and imidazole were studied using UV/vis and mass spectrometry. A bathochromic shift… Expand