Aliphatic proximity

After return to the Commander window, the reaction retrieval may be executed separately 629 Dicls-Aldcr reactions between aliphatic dienes and cyclic dicno-pliiles are found. This partial result can be narrowed down by restricting tlie reaction conditions by means of the fact editor, The search field codes for the yield and the temperature can be found to be RX.NYD and RX.T, respectively, either by browsing the database structure or by applying the Find option, as described in the first example. To ensure that the retrieved reaction conditions belong to the same experiment, both search terms must be connected by means of the PROXIMITY operator. Before the retrieval is started, the option "Refine results in... 

Although a maj ority of research activities were dedicated to cycloketone converting BVMOs, the recently discovered novel MOs also enable stereoselective oxidation of noncyclic ketones to esters. An aliphatic open-chain monooxygenase (AOCMO) from Pseudomonas Jluorescens DSM 50106 displays stereoselective biooxidation of terminal acyl-groups in proximity to hydroxyls (Scheme 9.23). The biooxidation gives acetic... 

Whether the SF5 group is aliphatic-, vinylic-, or aromatic bound does not seem to have much influence upon the fluorine chemical shifts observed. However, an SF5 group that is proximate to a functional group can have its chemical shifts, particularly those of the equatorial fluorines, influenced somewhat by that functional group. 

The CES family of proteins is characterized by the ability to hydrolyze a wide variety of aromatic and aliphatic substrates containing ester, thioester, and amide bonds (Heymann 1980, 1982). Cauxin is a member of the CES family, and is secreted from the proximal straight tubular cells into the urine in a species-, sex-, and age-dependent manner. Therefore, we postulated that cauxin was involved in an enzymatic reaction in cat urine and the products made by the reaction should vary with species, sex, and age. Based on this hypothesis, we searched for physiological substrates and products of cauxin in cat urine and identified 2-amino-7-hydroxy-5,5-dimethyl-4-thiaheptanoic acid, also known as felinine. 

The reaction of aliphatic and aromatic ketone oximes 97 with a dialkyl carbonate 98 in the presence of K2CO3 at 180-190 °C yields 3-alkyl-4,5-disubstituted-2(3//)-oxazolones 104 in 22-48% yields. Mechanistically, it is proposed that N-alkylation of the initially formed oxime O-carbonate 99 yields 100, which affords the enamine 101 in the presence of base. A [3,3] sigmatropic rearrangement ensues to produce 102, which then cyclizes to 104. In cases where 97 contains two methylene groups in proximity to the C=N bond, one of which is benzylic, the above reaction sequence is regioselective for the benzylic methylene group (Fig. 5.25 Table 5.6, Fig. 5.26). ... 

As regards organic contaminants, leachates from semi-coke contain compounds such as phenols, for example, cresols, resorcinols, and xylenols, which occur at mg/L concentrations. Indeed, Kahru et al. (2002) found total phenols at concentrations up to 380 mg/L in semi-coke dump leachates. Phenols also volatilize from such leachates, depending on temperature and pH (Kundel Liblik 2000). Atmospheric phenol concentrations of 4-50 xg/m3 have been observed in the proximity of leachate ponds (Koel 1999). Generally, aliphatic hydrocarbons, carboxylic acids, and organo-nitro and organo-sulpho compounds do not occur at elevated concentrations in leachates from Estonian semi-coke (Koel 1999). 

Because the forces of attraction prevail when molecules are brought into sufficiently dose proximity under normal conditions, release is best effected if both the strength of the interaction and the degree of contact are minimized. Aliphatic hydrocarbons and fluorocarbons achieve the former effect, finely divided solids the latter. Materials such as microcrystalline wax [64742 42-3] and hydrophobic silica [7631-86-9] combine both effects. Some authors refer to this combined effect as the ball bearing mechanism. A perfluoroalkylated fullerene nanosphere would perhaps be the ultimate example of this combined effect (17). These very general mechanistic remarks can be supplemented by publications on the mechanism of specific classes of release agents such as metallic stearates (18), fatty acids and fluorinated compounds (19), and silicone-coated rdease papers (20,21). The mechanism of release of certain problem adherents, eg, polyurethanes, has also been addressed (22,23). 

The Barton reaction [102], A photochemical exchange process between a nitrite group and a proximate nonactivated hydrogen has been called the Barton reaction. The process appears to be limited to aliphatic compounds (Eq. 52). 

As was mentioned earlier, polyethylenimine has many amine nitrogens in it, and these have the potential to act as nucleophiles (e.g., in an aminolysis reaction). In addition, they are locally concentrated (Figs. 2 and 3). Furthermore, polymers with attached aliphatic acyl groups provide apolar binding sites in proximity to amine residues of the polymer. One might expect, therefore, to find progressively enhanced rates of... 

Because the forces of attraction prevail when molecules are brought into sufficiently close proximity under normal conditions, release is best effected if both the strength of the interaction and the degree of contact are minimized. Aliphatic hydrocarbons and fluorocarbons achieve the former effect, finely divided solids the latter. Materials such as microcrystalline wax and hydrophobic silica combine both effects. 

Nagasawa and co-workers reported the use of a chiral bis-thiourea catalyst (108) for the asymmetric MBH reactions of cyclohexenone with aldehydes [95]. Since others had already shown that thioureas form hydrogen bonds with both aldehydes and enones, it was hypothesized that the inclusion of two thiourea moieties in close proximity on a chiral scaffold would organize the two partners of the MBH reaction and lead to enantiofacial selectivity. Initial studies showed that the achiral 3,5-bis-(trifluoromethyl)phenyl-substituted urea increased the rate of MBH reaction between benzaldehyde and cyclohexenone. These authors then showed that chiral 1,2-cyclohexyldiamine-linked bis-thiourea catalyst 108, used at 40 mol% loading in the presence of 40 mol% DMAP, promoted the MBH reactions of cyclohexenone with various aliphatic and aromatic aldehydes (40) to produce allylic alcohols in moderate to high yields (33-99%) and variable enantio-selectivities (19-90% ee Table 6.33). 

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