Hermann catalyst

De Meijere and coworkers developed a nice example where three C-C-bonds are formed in one domino process [36]. Thus, reaction of 6/1-48 with the Hermann-Beller catalyst 6/1-15 led to 6/1-50 as the only product (Scheme 6/1.10). It can be assumed that the Pd-compound 6/1-49 is an intermediate. 

Doyle MP (2004) Metal Carbene Reactions from Dirhodium(II) Catalysts. 13 203-222 Driefien-HOlscher B, see Hermanns E (2008) 23 53-66... 

Hermanns E, Hasenjager J, Driefien-Holscher B (2008) PEG-Modified Ligands for Catalysis and Catalyst Recycling in Thermoregulated Systems. 23 53-66 Hermanns J, see Schmidt B (2004) 13 223-267 Herrmann W, see Freimd C (2007) 22 39-77... 

Extensive studies of the Heck reaction in low-melting salts have been presented by Hermann and Bohm [86]. Their results indicate that the application of ionic solvents offers clear advantages over that of commonly used organic solvents (e.g., DMF), especially for conversions of the commercially interesting chloroarenes. Additional activation and stabilization was observed with almost all catalyst systems tested. Among the ionic solvent systems investigated, molten [NBu4]Br (mp =... 

The first examples of asymmetric Michael additions of C-nudeophiles to enones appeared in the middle to late 1970s. In 1975 Wynberg and Helder demonstrated in a preliminary publication that the quinine-catalyzed addition of several acidic, doubly activated Michael donors to methyl vinyl ketone (MVK) proceeds asymmetrically [2, 3], Enantiomeric excesses were determined for addition of a-tosylnitro-ethane to MVK (56%) and for 2-carbomethoxyindanone as the pre-nudeophile (68%). Later Hermann and Wynberg reported in more detail that 2-carbomethoxy-indanone (1, Scheme 4.3) can be added to methyl vinyl ketone with ca 1 mol% quinine (3a) or quinidine (3b) as catalyst to afford the Michael-adduct 2 in excellent yields and with up to 76% ee [2, 4], Because of their relatively low basicity, the amine bases 3a,b do not effect the Michael addition of less acidic pre-nucleophiles such as 4 (Scheme 4.3). However, the corresponding ammonium hydroxides 6a,b do promote the addition of the substrates 4 to methyl vinyl ketone under the same mild conditions, albeit with enantioselectivity not exceeding ca 20% [4],... 

Haber demonstrated that the production of ammonia from the elements was feasible in the laboratory, but it was up to Carl Bosch, a chemist and engineer at BASF, to transform the process into large-scale production. The industrial converter that Bosch and his coworkers created was completely revised, including a cheaper and more effective catalyst based on extensive studies in high-pressure catalytic reactions. This approach led to Bosch receiving the Nobel Prize in chemistry in 1931, and the production of multimillion tons of fertilizer per year worldwide, see also Agricultural Chemistry Catalysis and Catalysts Equilibrium Le Chatelier, Henri Nernst, Walther Hermann Ostwald, Friedrich Wilhelm. 

The first introduction of NHC ligands to ruthenium complexes for olefin metathesis catalysts was reported by Hermann et al. in 1998 [58]. These derivatives exhibit two unsaturated NHC ligands (20) and show little improvement in activity when compared to the parent bis(phosphine) complex 1 (Fig. 2). Due to the stronger a-donor ability of NHCs compared to phosphines, catalyst initiation by dissociation of one NHC is disfavored. Subsequently, the synthesis of phosphine-NHC complex 2 that contains a bulkier NHC ligand was reported by different research groups [2-5]. This complex... 

The first palladium-catalyzed coupling between a secondary amine and an aryl chloride was described by Beller, Hermann and co-workers in 1997 [70]. Use of palladacycle 12 as catalyst resulted in C-N bond formation in good yield for several secondary amines and electron-deficient aryl chlorides, Eq. (40). In these transformations, varying amounts of the regioisomeric product was observed, indicative that to some degree the reaction proceeds via a benzyne intermediate. 

The search for more stable or more reactive catalysts has produced many new leads. One of the most promising is represented by the paUadacycle (14), known as Hermann s catalyst. This can be used in Heck reactions at high temperatures (above 140 °C), which leads to high turnover numbers of up to 10 with electron-poor aryl bromides. ... 

Atropisomers of conformationally restricted bis-phenols have been popular ligands in several applications (Sch. 5, 8, 9, 11-13 Tables 4 and 5). Aluminum compounds prepared from bis-l,T-binaphth-2,2 -ol (BINOL) 40 and the derivatives 97 were examined as chiral catalysts in the reaction of methyl acrylate and cyclopentadiene by Maruoka, Concepcion and Yamamoto [50] and by Ketter, Glahsl and Hermann [47]. Four catalysts prepared from four derivatives of the 3,3 -bis-triarylsilyl derivatives of 97 and trimethylaluminum were examined in both toluene and dichloromethane the results are summarized in Sch. 26 [50]. Slightly higher asymmetric induction was observed in toluene and for the f-butyldiphenysilyl derivative 97b. The catalyst prepared... 

Narasaka has demonstrated that TADDOL-Ti dichloride prepared from TADDOL and Cl2Ti(OPr )2 in the presence of MS 4A acts as an efficient catalyst in asymmetric catalytic Diels-Alder reactions with oxazolidinone derivatives of acrylates, a results in extremely high enantioselectivity (Sch. 45) [112]. Narasaka reported an intramolecular version of the Diels-Alder reaction, the product of which can be transformed into key intermediates for the syntheses of dihydrocompactin and dihydromevinolin (Sch. 46) [113]. Seebach and Chapuis/Jurczak [114] independently reported asymmetric Diels-Alder reactions promoted by chiral TADDOL- and 3,3 -diphenyl BINOL-derived titanium alkoxides. Other types of chiral diol ligands were also explored by Hermann [115] and Oh [116]. 

Staudinger, Hermann (1881-1965). Fundamental research on high-polymer structure, catalytic synthesis, polymerization mechanisms, resulting eventually in development of stereospecific catalysts by Ziegler and Natta (stereoregular polymers). Nobel Prize 1963. 

---