A New Approach to Inducing Silicon Tethered Ring-closing Metathesis Reactions

Ring-closing metathesis reactions involving diallyldiphenylsilane and diallyloxydiphenylsilane were successfully performed by using only 0 01 mol or even less of Grubbs' catalyst 1. The effects of reaction parameters, such as solvents, temperature and concentration of the catalyst are discussed.

Modular Total Synthesis of (-)-Palmyrolide A and (+)-(5S,7S)-Palmyrolide A via Ring-Closing Metathesis and Alkene Isomerization

A pentamodule assembly approach has been established for total synthesis of the naturally occurring(-)-palmyrolide A and(+)-5,7-epi-palmyrolide A.By using the racemic tert-butyl carbinol-containing alkyl iodide,the two diastereoisomeric macrolides could be obtained from the same sequence of reactions,demonstrating the flexibility of the multimodule assembly strategy for diverted total synthesis.

Halogen Bond Catalysis on Carbonyl-Olefin Ring-Closing Metathesis Reaction:Comparison with Lewis Acid Catalysis

The carbonyl-olefin ring-closing metathesis reactions have become a powerful tool for carbon-carbon bond formation.In this work,the halogen bond catalysis and classical Lewis acid catalysis on the carbonyl-olefin ring-closing metathesis reaction were investigated by density function theory.For both the halogen bond catalysis and classical Lewis acid catalysis,the carbonyl-olefin ring-closing me-tathesis reaction occurs by[2+2]-cycloaddition process and[2+2]-cycloreversion process,the reaction energy barriers are low,there-fore,it can be performed easily at room temperature.The essential difference of the two kinds of catalysts is that the catalytic mecha-nism of halogen bond catalysis is mainly contribution of electrostatic interaction,while that of classical Lewis acid catalysis is mainly catalyzed by orbital interaction.The halogen bond donor catalysts(ICI_(3),IF_(3))are expected to be efficient catalysts for the reaction and further promote the chemical synthesis of carbonyl-olefin ring-closing metathesis reaction.

Syntheses of Macrocyclic Amides from L-Amino Acid Esters by RCM

A series of succinate-derived macrocyclic amides（1） was synthesized via ring-closing metathesis（RCM） as the key step. The substrate included 12 to 15 members. The metathesis precursors were obtained from the amide coupling of ten-butyl 3-carboxyhex-5-enoate（2） with numerous side-chain aikenylated amino acid esters of general type（3） derived from L-lysine and L-ornithine.

Topological effects of macrocyclic polymers:from precise synthesis to biomedical applications

Polymer chain architectures play a crucial role in the physical properties of polymers and this unique phenomenon has been recognized as the topological effects.As one of the most representative architectures,macrocyclic polymers characterized by the endless topology have received extensive attention due to their distinct physical properties as compared to the linear counterparts.To understand these differences and unravel the underlying mechanisms,there is a long pursuit to efficiently fabricate macrocyclic polymers.To date,both ring-closing and ring-expansion strategies have been developed,which drastically elevates the accessibility of macrocyclic polymers.The improved availability of macrocyclic polymers enables the further investigation of the biomedical applications and the preliminary results suggest that macrocyclic polymers outperform their linear analogs in terms of improving gene delivery efficiency,elevating blood circulation time,and enhancing colloidal stability of nanoparticles.