Isomerization derivative

A related scrambling of groups in a silene has also been reported by Eaborn (143) to explain the structure of compounds isolated from the thermolysis of tris(trimethylsilyl)fluorodiphenylsilylmethane at 450°C, where Me and Ph groups freely interchange between silicon atoms [Eq. (19)]. A related rearrangement is probably also involved in the photochemical silene-to-silene isomerizations derived from acylpolysilanes described earlier. 

Acid catalysed rearrangement of the tetrahydro 1-benzazepine sulfonamides 52 gave the 9-substituted sulfone derivatives 53 plus, in the case of 52b, the 7-substituted isomeric derivative... 

An isomeric derivative of natural rubber produced by a variety of chemical treatments. The products are resinous and find application as reinforcing agents in natural rubber compounds (particularly in shoe soles) and as rubber-to-metal adhesives. 

Condensation of 592 with phenacyl halides gave the imidazotriazino-indoles 594. However, the reaction with formamidine derivative 593 afforded isomeric derivative 595 (87MI5). 

The ring closure of 2-[iV-(2-hydroxyethyl)-Ar-mcthyl ]amino[ l, 2,41 triazolo[ 1,5-zz] pyrimidin-5-ones 333, promoted by PPA, gives the major compounds 36 and minor amounts of the isomeric derivatives 334 (Equation 59) <2002JHC319>. 

The bonding forces involved in hydrophobic interaction can be quite specific to the structure of the dye ions involved. A series of isomeric derivatives of 2-phenylazophenol-4-sulphonic acid, each containing a trifluoromethyl substituent, was synthesised recently. The aqueous solubility of these monosulphonated acid dyes was found to be dependent on the location of this specific grouping in the dye molecule [4]. 

Treatment of these complexes with excess phenylacetylene leads ultimately to the symmetrical triphenyl benzene as the main product, but the intermediate adduct IV, Os3(CO)9L2, exists in three isomeric forms which are considered to be related to the osmacyclopentadiene complex Os3(CO)9[C2(C6H5)2]2, obtained from reaction of diphen-ylacetylene with the Os3(CO)i2. The structure of this complex has been established by X-ray crystallography (132) to be that shown in Fig. 21, with R = Rl = Rz = R3 = Ph. The three isomeric derivatives in the case of the phenylacetylene adduct arise from the various permutations of the phenyl and hydrogen groups around the osmacyclopentadiene ring. 

Recently Cavaleiro et al. described an easy synthetic approach to glycoporphyrins from zinc(n) protoporphyrin-IX dimethyl ester 4 and O-allyl carbohydrate acetonides 5A-E (D-ribose (A), D-galactose (B), D-glucose (C), and two isomeric derivatives (D) and (E) of D-fructose) by cross-metathesis (Scheme 2).12 Two equivalents of each carbohydrate and the Grubbs catalyst were used, giving the carbohydrate derivatives 6 in a range of 74% to 93% yields. 

Me2Ph)(ri-C5Me5) -7-( r-H)-2,2,2-(CO)3-c/o.so-2,l-ReCBioHio] (127) which were characterized by X-ray diffraction (Chart 22). The nature of the isomerism derives from whether the B-H M bridge involves an a-BH (as in 126) or a p-BH (as in 127) in the rhenium-bonded CBBBti face, in combination with the relative disposition anti or syn) of the phosphine with respect to this hydride. A more detailed discussion of this system is presented elsewhere. ... 

In the reactions of cis- and rrans-2-aminomethyl-l-cyclohexanol or -1-cycloheptanol or cis- and trans-2-hydroxymethyl-l-cyclohexylamine or -1-cycloheptylamine with ethyl 4-chlorobenzimidate, the stereo- and regio-isomeric derivatives and homologs 164 and 165 were prepared (79T799). The amidine intermediate 166 of the benzimidate ring closure was also... 

The monobenzhydiyl derivative of (S)-binaphthol has played an important role, not only in the synthesis of chiral bisbinaphthyl crown ether derivatives, for example, (55)-124, containing two different bridges between the two binaphthyl units, but also in the provision of an entry into the constimtionally isomeric derivative (5S)-125. Rational stepwise syntheses of macrocyles containing three binaphthyl units have been devised and applied to the synthesis of (SSS)-126 and (RSS)-127. Cleariy, in all these procedures, the C2 symmetry of the chiral building block restricts the number of products (to one ) and defines the symmetries of the macrocycles formed. 

The mass spectra of a number of A-substituted isomeric derivatives based on the 3-thiomethyl-5-aminotriazole structure have been correlated with the type of cleavage of the substituent <83JCR(S)126>. 

Despite the many advantages of converting free sugars into their O-trimethylsilyl derivatives, the formation of anomeric and isomeric derivatives (see Section IV, p. 38) may constitute a problem, especially with complex mixtures. Much effort has, therefore, been expended in seeking carbohydrate derivatives, suitable for analysis, in which the anomeric center has been eliminated. This may conveniently be accomplished by oxidation to the acid or lactone, by... 

NMR spectra of 1,2,4-triazines are well documented, especially the XH and 13C spectra. The parent compound (1) shows three signals in the XH NMR spectrum, as expected, the shifts depending on the solvent as shown in Table 2. In liquid ammonia a tr-complex is formed. The signal for H-6 is a doublet of doublets, while the signals for H-3 and H-5 are simple doublets. Since to our knowledge coupling between H-3 and H-5 is never observed in simple 1,2,4-triazines, XH NMR spectroscopy provides a simple method to distinguish between isomeric derivatives. 

Eckstein (443) has prepared the isomeric derivatives of uridine-2 3 -0,0-cyclophosphorothioate where one or the other of the tw o free oxygen atoms is converted to a sulfur atom. The maximum velocity for the hydrolysis of these compounds is one-fifth that of U > p under comparable conditions while the Km value for one is identical to U > p and the other is larger by a factor of 8. 

SO2 inserts into metal-carbon a bonds18). The reaction is stereospecific with respect to the configuration at the a-carbon atom of the alkyl group19) and proceeds with inversion of configuration at the a-carbon atom, as shown on threo-erythro isomeric derivatives of C5H5Fe(CO)2CHDCHDC(CH3)3 by H NMR spectroscopy20 70). 

The rest of the cyclic terpenoid sulfides are complex mixtures of partially degraded and isomerized derivatives of the terpenoid sulfides which elute on the capillary GC column as a broad, unresolved hump. On Raney nickel reduction this fraction yields a complex mixture of naphthenic hydrocarbons which cannot be resolved further by GC analysis. 

In contrast to unsymmetrically substituted monocyclic tropolones (which usually give two isomeric derivatives), both benzo- and heterocyclotropo-lones form only one product, owing to the resonance inhibition of the tropolone ring. 

Mix each aliquot collected with an equal volume of hexane, and transfer to a separatory funnel. Extract this mixture with three 15-mL aliquots of water combine the water extracts, and calculate the percent concentration (P) of the monosulfonated derivative (a = 0.0513 mg/L/cm at 615 nm) and the isomeric derivative (a = 0.0478 mg/L/cm at 610 nm) by the equation... 

The abundant natural compound linalool (3) is an attractant for the Colorado potato beetle (CPB), Leptinotarsa decemlineata. Two isomeric derivatives of linalool, (Z)-5-(1.5-dimethylhex-4-enyldiene)-dihydrofuran-2-one (4) and ( )-5-(1.5-dimethylhex-4-enyldiene)-dihydrofuran-2-one (5), were synthesized and were found to be moderate antifeedants against the CPB. A lactone derived from linalool strongly affected the properties of the original compound linalool, which is an attractant to the CPB. A similar effect is seen with the activity of either linalool (3) or 4-isobutyl-5-isopropyl-5-methyl-dihydrofuran-2-one (6) to aphids. Compared to linalool, the lactone reduced the total time the aphid spent on the leaf.16... 

A reacts with methyl iodide, to yield three isomeric derivatives, C-E, C22H26N2O4. The >H spectra of C and D, which are summarized below, are very similar to that of A, apart from the 6H singlet, A, which has replaced a broad exchangeable 2H signal in the spectrum of A. The H spectrum of E is more complex, containing a total of four 3H singlets. 

Diquinone isomeric derivatives 71a and 71b can serve as examples of the A—D—A motif [119]. Interestingly, although both derivatives contain weak donors and weak acceptors moieties, they do give segregated stack-... 

Selenenylation of lithium enolates is particularly inqxntant in the case of unsymmetrical ketones, when the product of kinetic control is preferentially formed. The more-substituted isomeric derivative is prepared by the selenenylation of the corresponding enol acetate. An interesting base-catalyzed transse-lenenylation reaction of a-alkyl-a-phenylseleneno ketones to the less-substituted a -position has recently been reported for which steric crowding at the a-position appears to be an essential requirement. 

Acetylenic Mannich bases, upon deamination, tend to produce isomerized derivatives such as allenes or compounds of type 239, bearing the alkyne moiety as an end group, These compounds are cKcasionally found in the presenee of vinyl acetylenes... 

In cyclic acetals, IX may be substituted at C2, C4, and C5. A tram arrangement of substituents at C4 and C5 will be more stable than a cis arrangement, as is clearly shown by the quantitative measurements on the cyclic 0-isopropylidene derivatives of erylhro- and threo-1,2-diphenyl-1,2-ethanediol, and the qualitative evidence given in Section V. The order of stability for isomeric derivatives with substituents at C2 and C4 (or C5) cannot be predicted by the method used for the 1,3-dimethyl-cyclopentanes, since that takes into account the puckering of the cyclopentane ring. 

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