Synlett最新文献

We present our synthetic endeavors towards the Ganoderma meroterpenoid ganoapplanin. This natural product was isolated from a Ganoderma fungus in 2016 and was found to be an inhibitor for T-type voltage-gated calcium channels. Our synthetic approach is based on a powerful intramolecular Giese cyclization/intermolecular aldol cascade to link the northern aromatic to the southern terpenoid fragment. This article highlights the synthetic studies that ultimately led to the successful development of the key cascade reaction, culminating in the first total synthesis of ganoapplanin. 1Introduction2Synthesis of the Southern Terpenoid Fragment3Synthesis of the Northern Terpenoid Fragment4Triethylborane Mediated Giese Cyclization/Aldol Reaction Cascades5Completion of the Total Synthesis of Ganoapplanin6Conclusion.

We report here a Ni-NPs-catalyzed one-pot synthesis of 2-alkyl/aryl quinazolinone motifs via acceptorless dehydrogenation of alcohol, condensation of an aldehyde intermediate with 2-aminobenzamide, followed by a second dehydrogenation of the cyclized intermediate. The protocol is atom-economical and require earth-abundant Ni as the catalyst. The present report involves the annulation of 2-aminobenzamide with various types of primary alcohols, including aryl/heteroaryl methanol, and aliphatic alcohols, and produces high yields of the desired products under neat conditions. The catalyst was synthesized via a high-temperature pyrolysis strategy, using ZIF-8 as the sacrificial template. The Ni NPs@N-C catalyst was characterized by XPS, HR-TEM, HAADF-STEM, XRD, and ICP-MS. The catalyst is stable even in air at room temperature and displayed excellent activity in the acceptorless dehydrogenative coupling synthesis of quinazolinones and could be recycled five times without appreciable loss of its activity.

For hundreds of years, it seems that people have needed stirring to conduct chemical experiments. This operation can be seen everywhere in chemical, pharmaceutical, and materials laboratories and factories. People generally believe that stirring helps with processes such as material dispersion, dissolution, and collision, thereby enabling more-efficient reactions. However, why do chemical reactions that occur in Nature not require stirring? What are the facts? For this purpose, we investigated a total of 329 organic chemical reactions in eight categories and 25 types, including 26 chemical reactions magnified to gram or even kilogram levels. Under the same conditions of temperature, humidity, pressure, and reaction time, we compared the reaction yields under stirring and standing conditions. More than 600 results showed that stirring or not stirring had almost no effect on the efficiency of chemical reactions in solution. If most chemists performing reactions turned off the agitator, it would not be difficult to imagine how much electricity could be saved!

N-Formylation of anilines using a renewable aleuritic acid as an eco-friendly and sustainable formylating source has been developed. para-Substituted anilines generally provided good yields, while moderate yields were observed with meta- and ortho-substituted derivatives. In situ generated formic acid through oxidative cleavage of aleuritic acid serve as a formyl source, which has been confirmed through control experiments.

A new method for the O-methylation of cinnamic acid employing DMSO as the methylating agent has been devised, employing a Ni-DMAP complex as catalyst along with Ag₂O and dimethylamine as additives. This protocol demonstrates broad substrate compatibility and good tolerance towards various functional groups. The key advantages of this approach include the utilization of cost-effective catalysts, moderate to high yield of the products, and short reaction time.

The impetuous development of the pharmaceutical industry and material science stimulates the search for new synthetic approaches and new methods for the synthesis and functionalization of aza-heterocycles; these are some of the key objectives of modern organic chemistry. As a result, an advanced method towards the synthesis of functionalized N-heterocycles that circumvents the limitations associated with traditional methods needs to be devised. In recent decades, rearrangement/reorganization reactions have emerged as a powerful tool for the efficient synthesis of the aza-heterocycle. In this illustration, we summarize some our recent efforts in the development of few complex aza-heterocyclic cores.

1 Introduction

2 Skeletal Rearrangement of Small Heterocycles via Domino Ring-Opening and Ring-Closing (DROC) Strategy

3 Ru(II)-Catalyzed Skeletal Rearrangement of the Quinazoline Ring

4 Lewis Acid Catalyzed Skeletal Rearrangement of Furans to Indolizine Cores

5 Skeletal Rearrangement of Donor–Acceptor Cyclopropanes via Domino Ring-Opening and Ring-Closing (DROC) Strategy

6 Lewis Acid Mediated Skeletal Rearrangement of Donor–Acceptor Spirocyclopropylpyrazolones

7 Skeletal Rearrangement through Ring Distortion Strategy

8 Conclusion

The synthesis of short phosphorodiamidate morpholino oligonucleotides (PMOs) has been successfully achieved using azidoaryl carbamate protected chlorophosphoramidate monomers. The deprotection step carried out in a neutral medium with triphenylphosphine-based reagents avoids the need for chlorinated solvents. This method uses a meticulously tailored combination of resin support, solvents, deblocking agents, and coupling reagents to ensure efficient synthesis. Additionally, the azidoaryl carbamate protecting group has been adapted as an orthogonal protection, enabling the development of bi- and trifunctionalized PMOs for bioconjugation. These advancements are expected to broaden the potential applications of PMOs in biomedical research.

We report a useful synthetic approach to assemble in/in epoxide, in/out epoxide, and out/out epoxide in cage systems using the Corey–Chaykovsky reaction and the Peterson olefination as key steps. In this regard, a variety of pentacycloundecane (PCUD) based cage compounds containing oxirane rings with diverse stereochemical disposition were synthesized via a simple synthetic sequence. Five cage diones were used for this purpose, and the starting cage diones were prepared with easily accessible starting materials such as 1,4-hydroquinone derivatives and cyclopentadiene. Here, we have used the Diels–Alder (DA) reaction, a [2+2] photocycloaddition, the Corey–Chaykovsky reaction, and the Peterson olefination as crucial steps to prepare the target molecules.

A sequential Cu-catalyzed amidation and hydroxylation of p-dihalobenzenes is applied to synthesize acetaminophen. This method allows the direct introduction of acetamido and hydroxy groups under acid-free conditions without forming other regioisomers. By using a one-pot process, acetaminophen can be prepared with an overall yield of up to 74%.

This review summarizes various strategies that combine metathesis with diverse named and unnamed reactions to create molecular diversity in producing carbocycles, macrocycles, and heterocycles.

1 Introduction

2 Olefinations

3 Rearrangement

4 Allylation

5 Cycloadditions

6 Coupling Reactions

7 Grignard Reaction

8 Radical reactions

9 Conjugate Addition–Metathesis

10 Multicomponent Reactions

11 Miscellaneous

12 Conclusions