A new synthetic method for γ-butyrolactols by the paladium-catalyzed regioselective oxidation of 1-alken-4-ols

<div>We report here a catalytic, Markovnikov selective, and scalable synthetic method for the synthesis of saturated sulfur heterocycles, which are found in the structures of pharmaceuticals and natural products, in one step from an alkenyl thioester. Unlike a potentially labile alkenyl thiol, an alkenyl thioester is stable and easy to prepare. The powerful Co catalysis via a cobalt hydride hydrogen atom transfer and radical-polar crossover mechanism enabled simultaneous cyclization and deprotection. The substrate scope was expanded by the extensive optimization of the reaction conditions and tuning of the thioester unit.</div>

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A Short Synthesis of the Plant Alkaloid 4-Methyl-2,6-naphthyridine

Letters in Organic Chemistry ◽

10.2174/1570178616666181116110647 ◽

2019 ◽

Vol 16 (12) ◽

pp. 931-934 ◽

Cited By ~ 2

Author(s):

Alexandra Kamlah ◽

Franz Bracher

Keyword(s):

Pyridine Ring ◽

Cross Coupling ◽

Antirrhinum Majus ◽

New Synthesis ◽

Short Synthesis ◽

Regioselective Oxidation ◽

Key Steps

: A new synthesis of the 2,6-naphthyridine alkaloid 4-methyl-2,6-naphthyridine from Antirrhinum majus has been developed. Key steps are a regioselective oxidation of 3-bromo-4,5- dimethylpyridine to the corresponding 4-formyl derivative, and the annulation of the second pyridine ring by Suzuki-Miyaura cross-coupling using (E)-2-ethoxyvinylboronic acid pinacol ester as a masked acetaldehyde equivalent. This protocol gives the alkaloid in four steps starting from commercially available 3,4-dimethylpyridine in 15% overall yield. This annulation protocol should be useful for the synthesis of other condensed pyridines as well.

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Efficient CDI/CH3SO3H -Catalyzed, Microwave-Assisted Synthesis of 2-Substituted Benzothiazoles

Letters in Organic Chemistry ◽

10.2174/1570178615666180611120239 ◽

2018 ◽

Vol 16 (1) ◽

pp. 34-39

Author(s):

Yao-Wei Li ◽

Pei-Ming Zhang ◽

Rui Li ◽

Yan Bai ◽

Yu Yu ◽

...

Keyword(s):

Mass Spectrometry ◽

Carboxylic Acids ◽

1H Nmr ◽

Good Yield ◽

Microwave Assisted Synthesis ◽

Synthetic Method ◽

Benzothiazole Derivatives ◽

Microwave Assisted ◽

Highly Effective

CDI combined with CH3SO3H was found to be highly effective for the cyclization of 2-aminothiophenol derivatives with carboxylic acids under MW condition. Fourteen benzothiazole derivatives were synthesized in good yield and their structures were characterized by 1H-NMR, 13CNMR, IR and mass spectrometry. This simple, rapid synthetic method is believed to provide a useful process for the synthesis of 2-substituted benzothiazole compounds.

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4-Hydroxy Pyridinium Triflate@SiO2 Nanoparticles as a Novel Efficient Catalyst for Fries Rearrangement of Aryl Esters with High Selectivity

Current Organic Synthesis ◽

10.2174/1570179417666200713175943 ◽

2020 ◽

Vol 17 (8) ◽

pp. 654-660

Author(s):

Shermineh Sadat Ghalehbandi ◽

Dadkhoda Ghazanfari ◽

Sayed Ali Ahmadi ◽

Enayatollah Sheikhhosseini

Keyword(s):

High Selectivity ◽

Sio2 Nanoparticles ◽

High Yield ◽

Synthetic Method ◽

Functionalized Silica ◽

Efficient Catalyst ◽

Fries Rearrangement ◽

Free Condition ◽

Solvent Free Condition ◽

Work Up

Introduction: We developed a simple, fast and new method for the Fries rearrangement of aryl esters. Materials and Methods: 4-Hydroxy pyridinium triflate functionalized silica is a very efficient, reusable and economically available catalyst for the Fries rearrangement in solvent-free condition and under microwave irradiation. Results and Discussion: Also, a notable selectivity was observed in the presence of 4-hydroxy pyridinium triflate functionalized silica. Conclusion: Selectivity, shorter reaction time, high yield, and easy work-up are advantages of this synthetic method.

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