News&Event
28.A Concise and Diversity-Oriented Approach to the Synthesis of SAG Derivatives
N. D. Wang, J. Xiang, Z. Ma, J. M. Quan, J. H. Chen*, Z. Yang*
An efficient and rapid solution-phase combinatorial synthesis of the SAG library was developed. The salient features for this library synthesis is the application of carbothioamide-derived palladacycle-catalyzed Suzuki coupling reactions for the parallel synthesis of a series of pyridine-based biaryl aldehydes under aerobic conditions and a directN-alkylation of carbamates using NaH as base in DMF in the presence of catalytic amount of water. The resultant library has been submitted to biological screening to evaluate their potential role in the regulation of Hedgehog pathway.
27.Effect of LiCl on Tuning the Reactivity of Pd-TMTU Catalyzed Pauson-Khand Reactions
L. J. Deng, J. Liu, J. Q. Huang, Y. Hu, M. Chen, Y. Lan, J. H. Chen*, A. Lei*, Z. Yang*
A general and robust transition-metal-catalyzed Pauson-Khand reaction is still difficult to achieve. In this contribution, we describe our recent observations on the effect of lithium chloride on Pauson-Khand reactions catalyzed by palladium(II) chloride-tetramethylthiourea; this allows structurally diverse cyclopentenones to be prepared effectively.
26.Synthesis of Thiourea-Oxazolines, a New Class of Chiral S,N-Heterobidentate Ligands: Application in Pd-Catalyzed Asymmetric Bis-methoxycarbonylation of Terminal Olefins
B. Liang, J. Liu, Y. X. Gao, D. X. Shu, K. Wongkhan, Y. Lan, A. Li, A. S. Batsanov, J. A. H. Howard, T. B. Marder*, J. H. Chen*, Z. Yang*
Organometallics, 2007, 26, 4756
A new chiral S,N-heterobidentate thiourea−oxazoline ligand was synthesized and isolated as two atropoisomers (4a, 4b). The ligands were employed in Pd-catalyzed enantioselective bis(alkoxycarbonylation)s of terminal olefins under mild conditions, giving high yields and modest ee values, demonstrating the potential of such ligands for use in Pd-catalyzed carbonylative reactions. Molecular structures of 4a and of the PdCl2 complexes of 4a and 4bhave been determined by single-crystal X-ray diffraction. In both complexes, the ligands exhibit a bidentate S,N bonding mode.
25.A One-Pot Synthesis of Quinoline-based Tetracycles by a Tandem Three-Component Reaction
C. Che, J. Xiang, G. X. Wang, R. Fathi, G. J. M. Quan, Z. Yang*
A practical one-pot synthetic strategy for the efficient synthesis of a range of structurally interesting and bioactive quinoline-based tetracycles has been developed. A key step in the synthesis is a tandem three-component reaction of heteroaromatic amine, methyl 2-formylbenzoate and tbutyl isonitrile, followed by TFA-mediated lactamization via intramolecular aminolysis of an adjacent ester. Results related to a kinase-panel screening for several selected compounds are also discussed in this article.
24.An Efficient One-Pot Asymmetric Synthesis of Biaryl Compounds via Diels-Alder/Retro-Diels-Alder Cascade Reactions
Y. X. Liu, K. Lu, M. J. Dai, K. Wang, W. Wu, J. H. Chen*, Z. Yang*
A single-step chirality transfer method for the synthesis of axially chiral biaryl compounds by construction of the second aromatic ring via a Diels−Alder/retro-Diels−Alder cascade reaction is reported. This methodology should find broad application in the synthesis of natural products and asymmetric catalysts.
*This publication was highlighted on http://www.organic-chemistry.org/Highlights/2007/08October.shtm