Synthesis最新文献

The utilization of sulfur heterocycles in organic synthesis has attracted significant attention due to their wide-ranging applications. This review showcases the syntheses of diverse sulfur heterocycles embedded with amino acid derivatives, polycycles, spirocycles, cyclophanes, and other complex scaffolds. The reported methods extend beyond compound synthesis and highlight the use of different sulfur reagents for constructing sulfur heterocycles. This Review also discusses the utility of a variety of sulfur-containing starting materials for the generation of complex target molecules.

1 Introduction

2 Potassium Thioacetate

3 Thiazolidine-2,4-dione

4 Rhodanines

5 Sodium Sulfide

6 Thiotetronic Acid

7 Thiadiazoles

8 Thiophene

9 Rongalite

10 Sulfur Dioxide

11 Divinyl Sulfone

12 Sulfur Heterocycles Based on Boronic Acids

13 Miscellaneous

14 Summary

As an important complement to the Buchwald–Hartwig–Miura arylation, Pd-catalyzed γ-C–H arylations, including γ-C(sp³)–H and γ-C(sp²)–H arylations, provide a more direct route to install an aryl group on the less reactive γ-site of unsaturated carbonyl compounds, and have attracted considerable interest from the chemistry community in recent years. This review summarizes the applications of this method with both cyclic and linear unsaturated carbonyl compounds (aldehydes, ketones, esters, amide, and nitriles), as well as in the total synthesis of natural products (NPs), natural product skeletons, and bioactive analogues.

1 Introduction

2 γ-C–H Arylation of Cyclic Unsaturated Carbonyl Substrates

2.1 Exocyclic γ-Arylation

2.1.1 Unsaturated Ketones and the Corresponding Silyl-Dienol Ethers

2.1.2 Unsaturated Lactones

2.2 Endocyclic γ-C–H Arylation

2.2.1 Unsaturated Ketones and the Corresponding Silyl-Dienol Ethers

2.2.2 Unsaturated Lactones

2.2.3 Unsaturated Nitriles

3 γ-C–H Arylation of Linear Unsaturated Carbonyl Substrates

3.1 Unsaturated Aldehydes

3.2 Unsaturated Ketones

3.3 Unsaturated Amides

3.4 Unsaturated Nitriles

3.5 Silyl Ketene Acetals of α,β-Unsaturated Esters

4 Conclusion

A solvent-controlled divergent thiocyanation of carbazoles and di/triphenylamines has been developed. Using either CH₃CN/H₂O (3:1) or DMSO as the solvent, a facile and efficient protocol for the solvent-controlled divergent synthesis of mono- and di-thiocyanation of carbazoles and di/triphenylamines was achieved. The salient features of this transformation include simple and mild reaction conditions, easily available substrates, and broad substrate scope.

The 3-substituted-3-hydroxy-2-oxindole scaffolds are not only widely encountered in bioactive compounds but also serve as versatile building blocks for the construction of diverse valuable architectures. Although numerous synthetic methodologies have been developed over the past decades, the asymmetric addition of nucleophiles or their equivalents to isatin substrates has proved to be one of the most efficient strategies for the synthesis of chiral 3-substituted-3-hydroxy-2-oxindoles. This Short Review aims to summarize the significant progress achieved in this field in recent years, with particular attention paid to reaction development, mechanism, and stereo-induction models.

1 Introduction

2 Asymmetric Alkylation of Isatins

3 Asymmetric Alkenylation and Dienylation of Isatins

4 Asymmetric Alkynylation of Isatins

5 Asymmetric Allenylation of Isatins

6 Asymmetric Arylation of Isatins

7 Asymmetric Annulations of Isatins

8 Conclusions and Outlooks

A diversity-oriented total synthesis for Amaryllidaceae alkaloids incorporating the frequently found C3a-arylated hydroindole moiety was developed. Chiral-anion-induced gold(I) catalysis was employed for the cyclization of 1,4-diynes to the pyrrolidine and the installation of the all-carbon quaternary stereocenter. Both enantiomeric series of crinine-type alkaloids in high enantiopurity were accessible by this methodology. The formal synthesis of a wide range of Amaryllidaceae alkaloids is described, such as (+)-vitattine, (–)-epi-vitattine, (–)-elwesein, (–)-epi-elwesein, (–)-crinine, (–)-epi-crinine, (–)-buphanisine, (–)-flexinine, and (+)-gracilamine.

This Short Review summarizes the synthesis and applications of triarylboranes (BAr₃), including both homoleptic and heteroleptic species, with a focus on the modification of their electronic and structural properties via the introduction of meta-substituents with respect to the B atoms to their Ar groups. This approach constitutes a complementary alternative to conventional strategies for the design of BAr₃, which are usually based on a modification of their ortho- and/or para-substituents. An initial analysis revealed that CH₃ and F are the most common meta-substituents in hitherto reported BAr₃ (apart from the H atom). Thus, an extensive exploration of other substituents, e.g., heavier halogens, longer or functionalized alkyl groups, and aryl groups, will increase our knowledge of the structure and reactivity of BAr₃ and eventually lead to a range of new applications.

1 Introduction

2 Scope of this Review

2.1 The Electronic and Steric Influence of meta-Substituents

2.2 Molecular Transformations Mediated by meta-Substituted Boranes

2.3 Other Examples of meta-Functionalization of BAr₃

3 Conclusions and Perspectives

The tail-to-tail dimerization of acrylamides enables the formation of diamides. However, only one example of N,N-dimethylacrylamide has been described in the literature. Herein, an NHC-catalyzed tail-to-tail dimerization of acrylamides in moderate to excellent yields is presented. In this context, N-arylacrylamides are susceptible to the dimerization reaction, which features high reaction efficiency, good E-selectivity, and easy operation.

Copper-mediated reactions of α-diazo-β-keto sulfonamides led to a range of products, including alkynesulfonamides, enamines, and α-halosulfonamides, with no evidence for intramolecular C–H insertion in any of the reactions, in contrast to the reactivity of the comparable α-diazo-β-oxo sulfones. Use of copper(II) triflate (5 mol%) led to the isolation of a series of alkynesulfonamides (up to 12% yield) and enamines (up to 64% yield). Use of copper(II) chloride (5 mol%) led to the formation, in addition, of α-halosulfonamides; use of stoichiometric amounts of copper(II) chloride/bromide enabled facile halogenation of the β-keto sulfonamide to form α-halosulfonamides (up to 63% yield).