Second generation commercial catalysts

The two-directional tandem metathesis of 1 to 2 proceeded smoothly using 20 mol % of the second generation Grubbs catalyst (now commercially available only from Aldrich and from Materia) under an atmosphere of ethylene. The conversion of 2 to 3 took advantage of the differing reactivity of the two ketones. Addition of hydride to 2 from the less hindered face of the less hindered ketone delivered 4. 

It was observed that Pt/HZSM-5 was of higher catalytic activity than commercial C0M0/AI2O3 in the hydrodesulfurization of thiophene. Therefore, there is a possibility for using Pt/HZSM-5 as highly active, second generation hydrodesulfurization catalyst for petroleum feedstocks. 

Second generation Grubbs catalyst (commercially available)... 

First generation Grubbs catalyst Second generation Grubbs catalyst (commercially available) (commercially available)... 

RRM of enantiopure cyclopentene 406, induced by commercially available second-generation catalyst G was the key step in Blechert s total synthesis of the bis-piperidine alkaloid (-f)-astrophylline 408. Exposure of metathesis precursor 406 to only 1 mol% C provided within 2 h bicycle 407 in 82% yield (Scheme 78). 

The intermolecular C-H insertion on N-Boc-piperidine leads to the rapid access of the pharmaceutical agent threo-methylphenidate (30) [26], As this reaction is of commercial interest, a range of chiral catalysts have been examined [26], The best enantioselectivity was obtained with Rh2(S-biDOSP)2, which is a bridged second generation analog of Rh2(S-DOSP)4 [26a, b]. 

The second factor, as a practical consequence of the first, has been the early commercial availability of some of these catalysts, particularly the first generation catalyst G1 in 1996 and, some years later (1999), the second generation catalyst G2 (Figure 2.1). These catalysts are now routinely used in organic chemistry laboratories. 

Commercial plants Nine commercial plants have been licensed with a total capacity of 200,000 mtpy. The largest commercial installation is Lonza s 55,000-mtpy plant in Ravenna, Italy. Second generation process optimizations and catalyst have elevated the plant performances since 1998. 

The introduction of molybdenum by R. Schrock (Nobel Prize, 2005) and ruthenium catalyst systems by R. Grubbs (Nobel Prize, 2005), especially the commercially available Grubbs catalysP [bis(tricyclohexylphosphine)benzylidene ruthenium(IV) dichloride]. A, and its second-generation variant, B, shown below, " has led to many RCM applications in organic synthesis. ... 

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