Copper-Catalyzed Cascade Cyclization of Indolyl Homopropargyl Amides: Stereospecific Construction of Bridged Aza-[n.2.1] Skeletons was written by Tan, Tong-De;Zhu, Xin-Qi;Bu, Hao-Zhen;Deng, Guocheng;Chen, Yang-Bo;Liu, Rai-Shung;Ye, Long-Wu. And the article was included in Angewandte Chemie, International Edition in 2019.Quality Control of Methyl 2-thienylacetate This article mentions the following:
Catalytic cycloisomerization-initiated cascade cyclizations of terminal alkynes have received tremendous interest, and been widely used in the facile synthesis of a diverse array of valuable complex heterocycles. However, these tandem reactions have been mostly limited to noble-metal catalysis, and are initiated by an exo-cyclization pathway. Reported herein is an unprecedented copper-catalyzed endo-cyclization-initiated tandem reaction of indolyl homopropargyl amides, where copper catalyzes both the hydroamination and Friedel-Crafts alkylation process [e.g., I → II (85%)]. This method allows the practical and atom-economical synthesis of valuable bridged aza-[n.2.1] skeletons (n=3-6) with wide substrate scope, and excellent diastereoselectivity and enantioselectivity by a chirality-transfer strategy. Moreover, the mechanistic rationale for this novel cascade cyclization is also strongly supported by control experiments, and is distinctively different from the related gold catalysis. In the experiment, the researchers used many compounds, for example, Methyl 2-thienylacetate (cas: 19432-68-9Quality Control of Methyl 2-thienylacetate).
Methyl 2-thienylacetate (cas: 19432-68-9) belongs to esters. Esters are widespread in nature and are widely used in industry. In nature, fats are in general triesters derived from glycerol and fatty acids. Esters are responsible for the aroma of many fruits, including apples, durians, pears, bananas, pineapples, and strawberries. Many esters have the potential for conformational isomerism, but they tend to adopt an s-cis (or Z) conformation rather than the s-trans (or E) alternative, due to a combination of hyperconjugation and dipole minimization effects. The preference for the Z conformation is influenced by the nature of the substituents and solvent, if present. Lactones with small rings are restricted to the s-trans (i.e. E) conformation due to their cyclic structure.Quality Control of Methyl 2-thienylacetate
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics