Studies on the Total Synthesis of Pseudolaric Acid A Stereocontrolled Synthesis of the Seven-membered Lactone

The lactone 16 was obtained stereo- and regioselectively by a reaction sequence of 9 steps in 21% overall yield.

Strategies for constructing seven-membered rings:Applications in natural product synthesis

The seven-membered ring motifs are found in bioactive pharmaceuticals and a wide range of natural products,including alkaloids and terpenoids,which hold significant importance in synthetic chemistry and has garnered considerable attention from both academia and industry.Despite the challenges faced in the past decade,the total synthesis of natural products incorporating the non-aromatic cycloheptane skeletons remains a compelling pursuit.Recently,numerous elegant strategies for constructing the sevenmembered ring system have been successfully developed.This review focuses on the recent advancements in this field from 2017 to April 2023,highlighting key transformations utilized to construct the non-aromatic cycloheptane core structures and serves as a valuable guide for synthetic chemists engaged in the total synthesis of natural products containing seven-membered ring motifs.

Progress in organocatalytic asymmetric (4+3) cycloadditions for the enantioselective construction of seven-membered rings

Chiral seven-membered ring systems such as seven-membered carbocycles and heterocycles are widely found in natural products and pharmaceuticals.Therefore,the catalytic enantioselective construction of such frameworks has evoked considerable interest in the field of chemistry.Among the various approaches,organocatalytic asymmetric(4+3)cycloadditions are highly effective for the enantioselective construction of seven-membered rings.Over the past two decades,substantial efforts have been devoted to this field and chemists have developed various organocatalytic asymmetric(4+3)cycloadditions.This review summarizes the progress in organocatalytic asymmetric(4+3)cycloadditions from 2003 to early 2022 and provides insights into challenging issues faced in this research field,enabling the future development of this field.

Anodic Cyclizations, Seven-Membered Rings, and the Choice of Radical Cation vs.Radical Pathways

While many steps in an oxidative cyclization reaction can be important,it is the cyclization step itself that plays the central role.If this step does not proceed well,then optimization of the rest of the sequence is futile.We report here that the key to the cyclization is channeling the reaction down the correct pathway.Some reactions require the use of a radical pathway and some require the use of a radical cation pathway.An example of each is provided along with a strategy for accessing both pathways using a common intermediate.

Novel seven-membered ring-fused naphthalimide derivatives with potentials for cancer theranostics

Naphthalimide derivatives have good planarity and large conjugated structure and therefore possess photophysical properties and biological activities. Previously, our group discovered seven-membered heterocyclic derivatives via modifying 4-and 5-positions of naphthalimide skeleton and found the derivatives had good water solubility and showed large stokes shift and strong fluorescence in water. In this article, we designed and synthesized more seven-membered ring-fused naphthalimide derivatives(Y1-Y16)by introducing different substitutions on the imide group. Among them, Y1, Y5, Y9 were found to show similar cytotoxic activities with Amonafide against A549 and HL60 cells, with IC50values at 10^(-6)mol/L.What is more, the asymmetry derivatives(Y1 and Y5) showed high fluorescent quantum yields in the aqueous phase(Ф = 0.47). Considering the great fluorescence quantum yields in water and the potent anti-tumor activities of the representative seven-membered ring-fused naphthalimides, they have potentials to be used as agents for cancer theranostics.

Syntheses, Crystal Structures and NMR of Two Molybdenum Complexes with 2,3-Dihydroxynaphthalene

Two complexes [H3N（CH2）2NH2]2[MoO2（C10H8O2）2] （1） and （C7H10N2）2- [MoO2（C10H8O2）2] （2） were obtained at nearly the same reaction condition and characterized by IR, 1H and 13C NMR and single-crystal X-ray diffraction. Both of the complexes possess complex anion [MoO2（C10H8O2）2]2- which shows a pseudo-octahedrally coordinated fashion. In complex 1, ethyldiamine presents just as a cation. However, in complex 2, ethyldiamine combines with the acetyl acetone as a byproduct which is confirmed by NMR.

Recent advances in(4+3)cycloaddition of allenes

Allenes are a class of unsaturated compounds containing a propadiene structural moiety,exhibiting essential physiological,pharmacological,and various reactivities.Their(4+3)cycloaddition reaction has become an effective method for synthesizing seven-membered rings,especially for heterocycles.This method has been continuously improved and developed.Herein,we review the(4+3)cycloaddition of allenes,focusing on the developed methodologies and the outlook in this field from 2013 to 2023.

Rhodium(Ⅲ)-catalyzed benzo[c]azepine-1,3(2H)-dione synthesis via tandem C–H alkylation and intermolecular amination of N-methoxylbenzamide with 3-bromo-3,3-difluoropropene

Here, a rhodium(Ⅲ)-catalyzed benzo[c]azepine-1,3(2 H)-dione synthesis via tandem C-H alkylation and intramolecular amination of N-methoxylbenzamide with 3-bromo-3,3-difluoropropene as the alkylation agent is reported. The substituted benzamides and protected indoles are all tolerated, yielding the corresponding products in moderate to good yields. Further study revealed those bioactive compounds such as piperic acid and a key precursor of Roflumilast all perform well, highlighting the synthetic utility of this method.