Schrock molybdenum alkylidene catalyst enables selective formation of macrocyclic unsaturated lactones by ring-closing metathesis at high-concentration

Ring-opening Metathesis Polymerization Molybdenum(vi) Alkylidene Catalysts

S Chapter 1 Study of Chiral Arylimido Molybdenum ROMP Catalysts. Molybdenum ROMP catalysts with a chiral ortho-(phenethyl)phenylimido ligand have been prepared. Mo(CHCMe2Ph)(N-2-C 6H4-CHMePh)(O-2,6-C 6H3-Ph2)2 (1la) and Mo(CHMe 2Ph)(N2-C6H4-CHMePh)[BIPHENO(Me) 2(t-Bu) 4] (11b) were isolated and shown to effect the polymerization of 2,3-dicarbomethoxynorbonadienes. Highly-trans syndiotactic poly...

DFT study on the reaction mechanism of the ring closing enyne metathesis (RCEYM) catalyzed by molybdenum alkylidene complexes.

The ring closing enyne metathesis reaction (RCEYM) catalyzed by molybdenum based monoalkoxy pyrrolyl Schrock type catalysts has been studied by means of DFT (B3LYP-D) calculations. The two potential active alkylidene species as well as the three proposed reaction mechanisms (ene-then-yne, endo-yne-then-ene and exo-yne-then-ene) have been taken into account. Moreover, the influence on the exo- a...

Low catalyst loadings in olefin metathesis: synthesis of nitrogen heterocycles by ring-closing metathesis.

A series of ruthenium catalysts have been screened under ring-closing metathesis (RCM) conditions to produce five-, six-, and seven-membered carbamate-protected cyclic amines. Many of these catalysts demonstrated excellent RCM activity and yields with as low as 500 ppm catalyst loadings. RCM of the five-membered carbamate series could be run neat, the six-membered carbamate series could be run ...

Molybdenum-based complexes with two aryloxides and a pentafluoroimido ligand: catalysts for efficient Z-selective synthesis of a macrocyclic trisubstituted alkene by ring-closing metathesis.

Endo-selective enyne ring-closing metathesis promoted by stereogenic-at-W mono-pyrrolide complexes.

The utility of W-alkylidene complexes for enyne ring-closing metathesis is demonstrated in a direct comparison with Mo-based analogs. Tungsten complexes lead to less alkyne oligomerization and higher levels of endo-selectivity and enantioselectivity.