Regioselective Synthesis of Heteroaryl Triflones by LDA (Lithium Diisopropylamide)-Mediated Anionic Thia-Fries Rearrangement
摘要:
Novel heteroaryl triflones including oxindole, pyrazolone, pyridine, and quinoline derivatives have been regioselectively synthesized by LDA-mediated thia-Fries rearrangement for the first time. These reactions are also the first examples of the application of anionic thia-Fries rearrangement in heteroaromatic compounds.
The gold-catalyzed oxidation of N-tosyl-protected 6-alkynyl-3,4-dihydro-2H-pyridines was studied in detail to obtain divinyl ketones in which one of the double bond is embedded in a heterocyclic framework. The best reaction conditions were then extended to different types of substrates to assess the scope of the reaction. DFT calculations were exploited to gain insight into the regioselectivity and
A new class of conjugated strigolactone analogues with fluorescent properties: synthesis and biological activity
作者:Chaitali Bhattacharya、Paola Bonfante、Annamaria Deagostino、Yoram Kapulnik、Paolo Larini、Ernesto G. Occhiato、Cristina Prandi、Paolo Venturello
DOI:10.1039/b907026e
日期:——
A new class of strigolactoneanalogues has been synthesized. They differ from known molecules, both of natural and synthetic origin, in two main features. The conjugated system extends from the enol ether bridge to the A ring, the B ring is a heterocycle while the C ring is a cyclic ketone instead of a γ-lactone. The key step of the synthesis is a Nazarov cyclization on activated substrates. Bioassays
o-Benzenedisulfonimide has been used for the first time as a Brønsted acid catalyst to induce electrocyclization of dienones into cyclopentenones (Nazarov reaction). The catalyst has been used in various organic solvents or under solvent-free conditions and it is entirely recoverable from the reaction mixture. The versatility and the effectiveness of the proposed procedure is demonstrated on a wide range of both activated and inactivated substrates.