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Strem now offers XiMo metathesis catalysts

The discovery of olefin metathesis is a  landmark advancement in chemical synthesis.  In metathesis, the carbon-carbon double bond of two olefins are cleaved and two new double bonds are generated in a process that is often compared to a partner-swapping dance.  As a versatile, atom-economical process for C=C bond cleavage and formation, metathesis has found application across a broad range of platforms in industry and academia.  Importantly, the continuously expanding library of catalysts available has made metathesis more versatile than ever before.  Leading many of these advancements have been Mo-alkylidene complexes developed in the labs of Schrock and Hoveyda.  Known for their heightened reactivity and differentiated selectivity compared to related Ru carbene complexes, Mo alkylidenes have proven to be vital tools in metathesis.            

One exceptional demonstration of regio-/stereoselective metathesis is depicted in the macrocyclic ring-metathesis shown in Scheme 1.  In that work, a monoaryloxide pyrrolide (MAP) complex (cat. no. 42-0550) was shown to catalyze Z-selective RCM across a broad range of substrates to give E,Z-dienoates in 57-71% yield.  The selectivity of catalyst 42-0550 was attributed to the bulky m-terphenyl oxide group, and the activating effects of the electron-deficient pentafluorophenylimido ligand.    Importantly, Z-selectivity in this system was shown to compliment the E-selective process catalyzed by a well-known Ru-carbene catalyst.¹  Apparent in these investigations and others is the importance of ligand selection for achieving desired reaction outcomes. 

Scheme 1.  Stereoselective ring-closing metathesis (RCM) catalyzed by 42-0550.¹

Further demonstrating this point are catalysts featuring chiral octahydrobinaphtholate ligands (cat. no. 42-0530, 42-0540, 42-0560).  The directing effect of these groups has enabled unprecedented stereoselectivity for a diverse range of applications.²  The example in Scheme 2 shows an enantioselective ring-closing metathesis catalyzed by 42-0560.³  Other examples from the literature have demonstrated the use of these ligands in enantioselective Z-selective ring-opening/cross-metathesis⁴ and other other Z-selective homocoupling⁵ and cross metathesis (Scheme 3).⁶

Scheme 2.  Enantioselective ring-closing metathesis with chiral catalyst 42-0560.³

Scheme 3.  Z-selectivity in cross-metathesis with chiral catalyst 42-0540.⁶

In partnership with XiMo, Strem now offers Mo-alkylidene metathesis catalysts.   Reactivity and selectivity with a given substrate is highly dependent on the ancillary components of the metal complex.  To meet the diverse range of synthetic needs, therefore, our commercial offering includes a series of catalysts with proven combinations of imido and alkoxy ligands (Table 1).  All catalysts are available in powder form or as air-stable paraffin tablets.    

Table 1.  XiMo catalysts now available from Strem.

References:

1.   J. Am. Chem. Soc. 2014, 136, 16493.

2.   J. Am. Chem. Soc. 2011, 133, 11512.

3.   Nature 2008, 456, 933.

4.   J. Am. Chem. Soc. 2009, 131, 3844.

5.   J. Am. Chem. Soc. 2009, 131, 16630.

6.   Nature 2011, 471, 461.

Items Mentioned:

42-0510:  [2,6-Bis(1-methylethyl)benzenaminato(2-)](2,5-dimethyl-1H-pyrrol-1-yl)(4',6'- diphenyl[1,1':3',1''-terphenyl]-2'-olato)(2-methyl-2-phenylpropylidene) molybdenum(VI) (1572180-69-8)
42-0515: [2,6-Bis(1-methylethyl)benzenaminato(2-)](2,5-dimethyl-1H-pyrrol-1-yl)(4',6'-diphenyl[1,1':3',1''-terphenyl]-2'-olato)(2-methyl-2-phenylpropylidene) molybdenum(VI) in paraffin formulated pellet
42-0520: [2,6-Bis(1-methylethyl)benzenaminato(2-)](2,5-dimethyl-1H-pyrrol-1-yl)(2-methyl-2-phenylpropylidene)([1,1':3',1''-terphenyl]-2'-olato) molybdenum(VI) (1703808-70-1)
42-0525: [2,6-Bis(1-methylethyl)benzenaminato(2-)](2,5-dimethyl-1H-pyrrol-1-yl)(2-methyl-2-phenylpropylidene)([1,1':3',1''-terphenyl]-2'-olato) molybdenum(VI), paraffin formulated pellet (1703808-70-1)
42-0530: [2,6-Bis(1-methylethyl)benzenaminato(2-)][(1R)-3,3'-dibromo-2'-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-5,5',6,6',7,7',8,8'-octahydro[1,1'-binaphthalen]-2-olato-kO](2,5-dimethyl-1H-pyrrol-1-yl)(2-methyl-2-phenylpropylidene) molybdenum (VI) (1103220-99-0)
42-0535: [2,6-Bis(1-methylethyl)benzenaminato(2-)][(1R)-3,3'-dibromo-2'-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-5,5',6,6',7,7',8,8'-octahydro[1,1'-binaphthalen]-2-olato-kO](2,5-dimethyl-1H-pyrrol-1-yl)(2-methyl-2-phenylpropylidene) molybdenum (VI), paraffin pellets (1103220-99-0)
42-0540: (R)-1-((3,3'-Dibromo-2'-((tert-butyldimethylsilyl)oxy)-5,5',6,6',7,7',8,8'-octahydro-[1,1'-binaphthalen]-2-yl)oxy)-1-(2,5-dimethyl-1H-pyrrol-1-yl)-N-(2,6-dimethylphenyl)-1-(2-methyl-2-phenylpropylidene)molybdenum (VI) (1300026-28-1)
42-0545: (R)-1-((3,3'-Dibromo-2'-((tert-butyldimethylsilyl)oxy)-5,5',6,6',7,7',8,8'-octahydro-[1,1'-binaphthalen]-2-yl)oxy)-1-(2,5-dimethyl-1H-pyrrol-1-yl)-N-(2,6-dimethylphenyl)-1-(2-methyl-2-phenylpropylidene)molybdenum (VI) paraffin pellets (1887760-68-0)
42-0550: (2,5-Dimethyl-1H-pyrrol-1-yl)(2,2'',4,4'',6,6''-hexamethyl[1,1':3',1''-terphenyl]-2'-olato)(2-methyl-2-phenylpropylidene)[2,3,4,5,6-pentafluorobenzenaminato(2-)-κN] ,(T-4) molybdenum(VI) (1433803-79-2)
42-0555: (2,5-Dimethyl-1H-pyrrol-1-yl)(2,2'',4,4'',6,6''-hexamethyl[1,1':3',1''-terphenyl]-2'-olato)(2-methyl-2-phenylpropylidene)[2,3,4,5,6-pentafluorobenzenaminato(2-)-κN] ,(T-4) molybdenum(VI), paraffin pellets (1433803-79-2)
42-0560: (S)-1-((3,3'-Dibromo-2'-((tert-butyldimethylsilyl)oxy)-5,5',6,6',7,7',8,8'-octahydro-[1,1'-binaphthalen]-2-yl)oxy)-N-(2,6-diisopropylphenyl)-1-(2,5-dimethyl-1H-pyrrol-1-yl)-1-(2-methyl-2-phenylpropylidene)molybdenum (VI) (1196674-83-5)
42-0565: (S)-1-((3,3'-Dibromo-2'-((tert-butyldimethylsilyl)oxy)-5,5',6,6',7,7',8,8'-octahydro-[1,1'-binaphthalen]-2-yl)oxy)-N-(2,6-diisopropylphenyl)-1-(2,5-dimethyl-1H-pyrrol-1-yl)-1-(2-methyl-2-phenylpropylidene)molybdenum (VI) paraffin pellets (1196674-83-5)
42-0575: [2,6-Bis(1-methylethyl)benzenaminato(2-)]bis(1,1,1,3,3,3-hexafluoro-2-methyl-2-propanolato-κO)(2-methyl-2-phenylpropylidene)-, (T-4) molybdenum, paraffin pellet (139220-25-0)
13-1905: Triethylaluminum paraffin pellet (97-93-8)

Related Resources:

Catalysis Product Family
Metal Catalysts for Organic Synthesis
Metathesis Catalysts
Metathesis Catalysts Developed by XiMo