The stability of second generation Grubbs alkylidenes to primary amines relative to the first generation derivatives is investigated. For both Grubbs alkylidene derivatives, the tricyclohexylphosphine (PCy3) ligand is displaced by n-butylACHTUNGTRENNUNGamine and diethylenetriamine. However, while displacement of PCy3 in first generation Grubbs alkylidene derivatives results in decomposition of ...

A novel chiral magnesium bisamide has enabled the development of effective asymmetric deprotonation protocols at substantially more elevated temperatures. This new, structurally simple, C(2)-symmetric magnesium complex displays excellent levels of asymmetric efficiency and energy reduction in the synthesis of enantioenriched enol silanes.

Imido alkylidene complexes of Mo and W and oxo alkylidene complexes of W that contain thiophenoxide ligands of the type S-2,3,5,6-Ph4C6H (STPP) and S-2,6-(mesityl)2C6H3 (SHMT = S-hexamethylterphenyl) have been prepared in order to compare their metathesis activity with that of the analogous phenoxide complexes. All thiolate complexes were significantly slower (up to ∼10× slower) for the metathe...

The synthesis, single crystal X-ray structure and activity in olefin metathesis of novel anionic tungsten imido alkylidene complexes [1,3-bis-(2,4,6-trimethylphenyl)imidazolinium](+) [W(N-2,6-iPr2C6H3)(CHCMe2Ph)(2,5-Me2Pyr)2Cl](-), [1,3-bis-(2,4,6-trimethylphenyl)imidazolinium](+) [W(N-2,6-iPr2C6H3)(CHCMe2Ph)(2,5Me2Pyr)2(OC6F5)](-), and [1,3-bis-(2,6-diisopropylphenyl)imidazolinium](+) [W(N-2,6...

In this paper we describe the syntheses of several new stereogenic-at-metal imido alkylidene complexes of molybdenum, Mo(NR)(CHR′)(X)(Y), many of which had to be prepared through selective nucleophilic displacement reactions in imido alkylidene complexes. The reported compounds include Mo(NAd)(CHCMe2Ph)(MesPyr)2 (1a; MesPyr = 2-mesitylpyrrolide, Ad = 1-adamantyl), Mo(NAd)(CHCMe2Ph)(2-CNPyr)2 (1...

Effects of arylimido ligands on the ring-opening metathesis polymerization (ROMP) norbornene (NBE), norbornadiene (NBD), and tetracyclododecene (TCD) were investigated using a series (arylimido)niobium(V)–alkylidene complex catalysts, Nb(CHSiMe3)(NAr)[OC(CF3)3](PMe3)2 [Ar = 2,6-Me2C6H3 (1), 2-MeC6H4 (2), 2,6-Cl2C6H3 (3)]. The catalytic activity in ROMP NBE for 1 was higher than 2 3 (toluene at ...

Natural products and their signature fragments are an enduring resource for identifying biological modulators. A number of biologically active alkaloids, such as strychnofoline and isorhynchophylline (Fig. 1), feature spiroindolizidine oxindoles. This fragment is considered ‘privileged’ for potential therapeutic investigation and there is much interest in developing expedient synthesis of such ...

This paper reports the synthesis of polyene oligomers ("oligoenes") that contain up to 15 double bonds that are identical to the "all five-membered ring" species formed through cyclopolymerization of diisopropyldipropargylmalonate. The oligoenes contain an isopropylidene unit at each end. The isolated oligoenes range from the "dimer" (a pentaene, (E)-di-1,2-[1-(2-methyl-propenyl)-4,4-di-iso-pro...

The 3-alkylidene-3H-indole 1-oxide functional group found in the naturally occurring alkaloid avrainvillamide has been synthesized by a cross coupling-reductive condensation sequence and found to undergo reversible addition of oxygen- and sulfur-based nucleophiles.