Synlett

An efficient and simple synthesis of various 3-(trifluoromethyl)chromones from enamino ketones is described. The key step in the synthesis involves the introduction of a trifluoromethyl (CF3) moiety onto a chromone structure. The significant features of this method include simple operational procedures, the high purity and yield of the product, and excellent regioselectivity.

Carbon–carbon and carbon–heteroatom bond-formation reactions catalyzed by benign and inexpensive metals are of much interest in organic synthesis, as these reactions provide green and cost-effective routes. This account summarizes our recent contributions to the construction of carbon–carbon and carbon–heteroatom bonds by using benign-metal catalysts. A number of carbon–heteroatom bond formations, including C–N, C–O, C–S, C–Se, C–Te, and C–P bond formations, are discussed. Mechanistic insights into several reactions are also reported1 Introduction2 C–C Bond Formation3 C–N and C–O Bond Formation4 Carbon–Chalcogen (C–S, C–Se, C–Te) and C–P Bond Formation5 Conclusions

A plethora of bioactive compounds and natural products bears an azole subunit within their complex structural frameworks. A footstep to realize those complex structures in atom economic fashion rely on the direct functionalization of C–H bonds adjacent to an azole group. In addition, the resulting functionalized azole compounds can be simply modified into practically significant genre of α-functionalized carboxylic acids that are otherwise inaccessible through a formal α-functionalization strategy. In this Account, we describe an up-to-date progress on the functionalization of a methyl and/or methylene group(s) adjacent to an azole ring enabled by late and earth-abundant transition metals. Contributions made by our group and that by others in the field are elaborated in this Account article.1 Introduction2 Mode of Reactivity of C–H Bonds Next to Azoles under Transition-Metal Catalysis3 Pd-Catalyzed Functionalization of Alkyl Groups Adjacent to an Azole Ring3.1 Functionalization through C–C Bond Formation3.2 Functionalization through C–Heteroatom Bond Formation4 3d-Metal-Catalyzed Functionalization of Alkyl Groups Adjacent to an Azole Ring5 Other Metal-Catalyzed Functionalization of Alkyl Groups Adjacent to an Azole Ring6 Conclusion and Future Prospects

A variety of oxygen, nitrogen and sulfur heterocyclic compounds are synthesized via one-pot multicomponent Prins, aza-Prins, thia-Prins, oxonium-ene, iminium-ene and thionium-ene cyclization reactions. The reactions proceeds with high diastereo- and regioselectivity. Importantly, C–C, C–N, C–O and C–S bonds are formed in a singsle step. These procedures are extended for the synthesis of biologically active molecules and natural products.1 Introduction2 Prins Cyclization Reactions3 Oxonium-Ene Cyclization Reactions4 Conclusion

We have developed an iron-catalyzed synthesis of pyrrolo[2,1-a]isoquinoline derivatives with tetrahydroisoquinolines, arylacyl bromides, and nitroolefins. Highly functionalized pyrrolo[2,1-a]isoquinolines can be obtained in moderate to good yields through a three-component N-alkylation/oxidative 1,3-dipolar cycloaddition/elimination/aromatization cascade. The obtained products in this study can be easily modified by easy chemical transformations to structurally complex molecules bearing privileged framework.

A concise catalytic asymmetric approach to naturally occurring Amaryllidaceae alkaloids sharing a 5,10b-ethanophenanthridine skeleton [(–)-oxomaritidine, (–)-dihydromaritidine, (–)-maritidine, and (–)-epi-maritidine] has been envisioned. The key intermediate in this strategy was obtained by a Pd(0)-catalyzed decarboxylative allylation of a 2-arylcyclohexan-1-one-derived allylenol carbonate (87%, 96% ee).

A boronic acid catalyzed one-pot reduction of quinolines with Hantzsch ester followed by N-arylation via external base-free Chan–Evans–Lam coupling has been demonstrated. This step-economical synthesis of N-aryl tetrahydroquinolines has been accomplished from readily available quinoline, Hantzsch ester, and arylboronic acid under mild reaction conditions. The dual role of boronic acid as a catalyst (in the reduction of quinolines) and a reagent (in the N-arylation) has been realized for the first time. The use of an inexpensive N-arylation protocol, aerobic reaction conditions, and functional group diversity are important practical features.

A concise total synthesis to generate synthetically challenging steroids scaffolds is reported utilizing palladium-catalyzed dearomatization cyclization for the key cyclization step, enabling the divergent synthesis of 6,6,6,5-tetracyclic steroids cores through both ligand and reaction condition control. We have started from the simple starting materials 2,4,6-trihydroxybenzoic acid and 2-methylcyclopentane-1,3-dione to selectively generate complex steroid scaffolds in a 12-step operation.

A mechanochemical asymmetric transfer hydrogenation (ATH) of diketones in the presence of a ruthenium complex under solvent-free conditions was developed to provide chiral 1,3-diol derivatives. This protocol benefits from rapid reaction kinetics, no use of solvents, and excellent enantioselectivity. In addition, the mechanochemical ATH reaction can easily be performed on a gram scale.

Synlett 2022; 33: A133-A150DOI: 10.1055/s-0040-1720570Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals:Table of contents