2-Adamantyl catalyst

Tertiary alkyl chlorides have been converted to the tertiary nittiles with trimethylsilyl nittile ia dichioromethane ia the presence of SnCl (131). The reaction was appHed to the synthesis of several bridgehead nittiles, such as 1-adamantyl and 1-diamantyl nittiles from the corresponding chloro or bromo derivatives usiag SnCl or AIBr. catalysts (132). 

For a chiral molybdenum-based catalyst available in situ from commercial components, see (a) Aeilts SL, Cefalo DR, Bonitatebus PJ, Houser JH, Hoveyda AH, Schrock RR (2001) Angew Chem Int Ed 40 1452 (b) For the first enantiomerically pure solid-sup-ported Mo catalyst, see Hultzsch KC, Jernelius JA, Hoveyda AH, Schrock RR (2002) Angew Chem Int Ed 41 589 (c) For a chiral Mo catalyst, allowing RCM to small- and medium-ring cyclic amines, see Dolman SJ, Sattely ES, Hoveyda AH, Schrock RR (2002) J Am Chem Soc 124 6991 (d) For a novel adamantyl imido-molybdenum complex with advanced selectivity profiles, see Tsang WCP, Jernelius JA, Cortez GA, Weatherhead GS, Schrock RR, Hoveyda AH (2003) J Am Chem Soc 125 2591... 

In 1993 Burk, Brown, and coworkers confirmed that DuPHOS complexes exhibit the same anti-lock-and-key mechanistic motif as seen for aryl phosphine ligated catalysts [41], In 1998 by Burk and coworkers reported an unexpected and interesting result [34], With substrates having R<, = aryl, selectivity of 99% e.e. for the S product resulted from (S,S)-Me-DuPHOS-Rh hydrogenations, but the R product was obtained with similarly high enantioselectivity when Ra = t-Bu or adamantyl. In other words, the simple change of an aryl substituent to a bulky alkyl completely reverses the sense of enantioselection. 

Catalyst 329, prepared from trimethylaluminum and 3,3/-bis(triphenylsily 1)-1,1 /-bi-2-naphthol, allowed the preparation of the endo cycloadduct (2S )-327 with 67% ee. The use of non-polar solvents raised the ee, but lowered the chemical yield213. Recently, it was reported that the reaction to form 327 exhibited autoinduction when mediated by catalyst 326214. This was attributed to a co-operative interaction of the cycloadduct with the catalyst, generating a more selective catalytic species. A wide variety of carbonyl ligands were tested for their co-operative effect on enantioselectivity. Sterically crowded aldehydes such as pivaldehyde provided the best results. Surprisingly, 1,3-dicarbonyl compounds were even more effective than monocarbonyl compounds. The asymmetric induction increased from 82 to 92% ee when di(l-adamantyl)-2,2-dimethylmalonate was added while at the same time the reaction temperature was allowed to increase by 80 °C, from -80 °C to 0°C. 

Scheme 8.8 Synthesis of a monolith-supported second generation catalyst immobilized via the NHC-ligand. R = adamantyl, mesityl.

Cahonic iridium complexes bearing imidazol-2-ylidene hgands were applied as TH catalysts by Hillier et al. [48]. Here, [lr(cod)(py)(L)]Pp6 (L= IMes, l,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (53a), IPr, l,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (53b) and ICy, l,3-bis(cyclohexyl)imidazol-2-ylidene (53c) were employed as catalysts for TH from 2-propanol to various unsaturated substrates, and compared to [lr(cod)(py)(PCy3)]PF6 and complexes formed in situ from [Ir(cod)(py)2]PF,5 and diazabutadienes (RN=CHCH=NR, DAB-R R = cyclohexyl, DAB-Cy 2,4,6-trimethylphenyl, DAB-Mes adamantyl, DAB-Ad 2,4,6-trimethoxyphenyl, DAB-trimethoxyphenyl). AH complexes were achve catalysts for the TH of acyclic ketones, with complex 53c being the most achve, showing 100% conversion of BuC(0)Me and PhC(0)Ph in 25 and lOmin, respechvely, using 0.025 mol% of catalyst and KOH in PrOH at reflux (Scheme 4.20). 

Song and co-workers have taken a variety of aldehydes 344 and treated them with A -adamantyl carbene 1 and trimethylsilyl ketene acetal 345 to produce Mukaiyama aldol products 346 in good yield (Eq. 34) [170], The carbene presumably acts as a Lewis base to activate the silicon - oxygen bond in order to promote reactivity of the enol silane. The catalyst loading can be reduced to as low as 0.05 mol% without a change in yield. 

Intermolecular amination experiments described by Muller using 02NC,5H4S02N=IPh (NsN=IPh) as the nitrene source underscore the value of certain rhodium(II) catalysts for C-H insertion (Scheme 17.5) [12, 34—36]. In accord with Breslow s finding, dirhodium carboxylates were demonstrated to catalyze the amination of allylic, benzylic, and adamantyl substrates. Notably, structurally related tetracarboxamide dimers fail to give... 

The use of the step 2 carbene reagent catalyst, l,3-di-l-adamantyl-imidazole-2-ylidene, (I), in preparing macrocyclic polyester oligomers is described by... 

Figure 7.15 Adamantyl-linked proline is an effective aldol catalyst in the presence of 3-cyclodextrin.

FeCl3-doped K10 montmorillonite was used to promote adamantylation of benzene to form 1-phenyl and 1,3-diphenyladamantanes in ratios depending on the amount of catalyst 193... 

The solid acid catalyzed adamantylation of substituted benzene derivatives was studied with the aim to achieve high para regioselectivities. Of various acidic resins, zeolite HY, sulfated zirconia, perfluorolkanesulfonic acids, and phosphotungstic acid, Amberlyst XN-1010 was found to be the catalyst of choice to afford para-substituted alkylbenzenes with selectivities exceeding 70%.398 In further systematic studies with a Nafion-H-silica nanocomposite catalyst,399 and various... 

Manganese(III) acetate is poorly reactive with saturated hydrocarbons.514 However, oxidation of adamantane by Mn(OAc)3 in trifluoroacetic acid gives relatively high yields of 1-adamantyl trifluoroacetate, showing a preferential attack at tertiary C—H bonds.515 Oxidation of n-alkanes by air in the presence of manganese catalysts constitutes the basis for an industrial process for the manufacture of synthetic fatty acids from n-alkanes of petroleum origin, which has been commercially developed in the Soviet Union.516... 

Boron tris(triflate) has also been tested in the adamantylation of benzene and toluene with 1-haloadamantanes [Eq. (5.87)] and2-haloadamantanes.232B(OTf)3 is a highly active catalyst to promote the transformation in very short time under mild conditions to yield isomeric aryladamantanes and adamantane byproduct (Table 5.15). Of the isomeric 1-tolyladamantanes, 1-meto-tolyladamantane predominates, whereas the para isomer is the main product of the 2-tolyladamantanes. The ortho isomers were... 

Treatment of adamantane with aluminum halide catalysts in the presence of nonane or 2,3,5-trimethylhexane results in the formation of a mixture of methylated adamantanes 354f Apparently, the 1-adamantyl cation generated by Lewis acid catalysts can initiate intermolecular alkyl shifts (presumably via attack on olefinic intermediates). 

To a suspension of magnesium (1.64 g, 67.5 mmol in 30 ml of THF, there is added a solution of 1.4 g (4.5 mmol) of 2-(l-adamantyl)-4-bromoanisole and 0.39 ml of dibromoethane in 10 ml of THF. The mixture is stirred until the reaction is initiated and then there is slowly added a solution of (40.8 mmol) of 2-(l-adamantyl)-4-bromoanisole in 90 ml of THF. The mixture is refluxed for 2 hours, and then cooled to 20°C. After that 6.2 g (45 mmol) of anhydrous ZnCI2 are added. The mixture is stirred for 1 hour at 20°C at which point 7.95 g (30 mmol) of methyl 6-bromo-2-naphthoate are added followed by addition of 300 g of NiCI2/l,2-(diphenylphosphino)ethane-complex as the catalyst. The mixture is stirred again for 2 hours at 20°C, poured into water, extracted with CH2CI2 dried and evaporated. The product is isolated by column... 

Another reported synthesis of symmetrical spiro-1,3-dithietanes 163a-d substituted with an adamantyl moiety is based on the [2+2] cycloaddition of two molecules of variously substituted adamantane-2-thiones <1997BCJ509>. With methanesulfonic acid as an acidic catalyst, the reaction provided 1,3-dithietanes 163a-d in high yields at ambient temperature. A similar reaction was performed with phosphorus pentachloride as the catalyst (Equation 22 Table 8) <2002AXCo231>. 

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