W-alkylation

Both common and systematic names of compounds are used throughout this volume, depending on which the Editor-in-Chief feels is most appropriate. Preparations appear in the alphabetical order of names of the compound or names of the synthetic procedures. The Chemical Abstracts indexing name for each title compound, if it differs from the title name, is given as a subtitle. Because of the major shift to new systematic nomenclature adopted by Chemical Abstracts in 1972, many common names used in the text are immediately followed by the bracketed, new names. Whenever two names are concurrently in use, the carre CChemical Abstracts name is adopted. The prefix n- is deleted from -alkanes and w-alkyls. All reported dimensions are now expressed in S st me International units. 

The preparation of W-alkyl derivatives of 6-benzyl-3,5-dioxo-l,2,4-triazine by hydrolysis of the corresponding alkylmercapto derivatives was systematically studied by Cattelain. The conversion to known alkyl derivatives of dioxotriazines was used to determine the structure of alkylated methylmercapto derivatives. As will be shown later (e.g., Section H,B,4,b) this procedure has a general preparative significance for 1-alkyl derivatives of 6-azauracil. ... 

Compared with sodium w-alkyl sulfates the ester sulfonates with the same number of carbon atoms in the hydrophobic chain have lower CMC values because the methyl group also contributes to the micellization. 

In 2000, Woodward et al. reported that LiGaH4, in combination with the S/ 0-chelate, 2-hydroxy-2 -mercapto-1,1 -binaphthyl (MTBH2), formed an active catalyst for the asymmetric reduction of prochiral ketones with catecholborane as the hydride source (Scheme 10.65). The enantioface differentiation was on the basis of the steric requirements of the ketone substituents. Aryl w-alkyl ketones were reduced in enantioselectivities of 90-93% ee, whereas alkyl methyl ketones e.g. i-Pr, Cy, t-Bu) gave lower enantioselectivities of 60-72% ee. 

FIG. 4 Dependence of the extraction rate constants, k, of Zn(II) and Ni(II) on the number of carbon atoms in the substitution of w-alkyl dithizones. The solid lines trace the observed values and the broken lines the values predicted from the aqueous mechanism. 

TABLE 6.1. Fluorine 8 Values for Perfluoro-w-Alkyl Halides... 

The method allowed the authors to characterise a pine pitch (viscous tar derived from the distillation of wood of pine trees). The main constituents detected by headspace SPME result from the pyrolysis of the lignin, guaiacol (11) and its p-w-alkyl derivatives [methyl... 

In terms of economical synthetic approaches to indoles, the synthesis of this heterocycle from anilines and trialkylammonium chlorides was effected in an aqueous medium (H20-dioxane) at 180°C in the presence of a catalytic amount of ruthenium(III) chloride hydrate and triphenylphosphine together with tin(II)chloride <00TL1811>. Muchowski devised a novel synthetic route to indole-4-carboxaldehydes and 4-acetylindoles 86 via hydrolytic cleavage of W-alkyl-5-aminoisoquinolinium salts 85 to homophthaldehyde derivatives upon heating in a two phase alkyl acetate-water system containing an excess of a 2 1 sodium bisulfite-sodium sulfite mixture <00JHC1293>. 

Hertzog, K., Naumann, P., and Schuelke, U., Combined Production of Substituted w-Alkyl l-a,a-Bisphosphonic Acids and Alkyl Phosphites, East German Patent 222,599, 1985. 

Chlorodialkylphosphines are important synthetic intermediates in organophosphorus chemistry. In the chemical literature there is a widespread view that the simple one-step Grignard method is not suitable for the preparation of these compounds because of dominant trisubstitution and the formation of difficultly separable mixtures.12 Although this is true for the w-alkyl compounds, the present preparation demonstrates that in the case of branched primary alkyl compounds and secondary and tertiary alkyl compounds the method can be very convenient and can give pure products. The submitters have prepared 13 chloro-diisobutylphosphine (45-50%), chlorodi-sec-butylphosphine (75-80%), chlorodi-f-butylphosphine (65-70%), and chlorodicyclo-hexylphosphine (60-65%) in analogous manner. 

The use of dimethyl sulphoxide as a dipolar aprotic solvent is well known,7 and the present method can be regarded as a model procedure and has been applied to the preparation of a number of N-w-alkyl-pyrroles and N-w-alkyl indoles.8 The yield of N-benzylindole is considerably higher than in previously reported preparations and is as good as that reported for the preparation of N-methylindole in liquid ammonia.4 The present method is, however, less laborious and quicker to carry out. Very high yields are obtained in reactions using w-alkyl halides and moderately good yields with secondary alkyl halides. The reactions should be compared with those recently reported for pyrryl-thallium.9... 

Mono-W-alkylation of anilines under soliddiquid two-phase conditions... 

Higher yields of W-alkylated derivatives (>75%) have been reported for reactions in aq. NaOH-MeCOEt, with TEBA-C1. i icjind liquid two-phase system at 20°C using Aliquat. 

Kazmaier and coworker described a simple approach to several cyclic peptido-mimetics containing a W-alkylated amino acid via Ugi reaction and a RCM (Scheme 19) [86, 87]. W-terminally protected Aloe amino acids c and aUyl isocyanides d were used in an Ugi-4CR to give the linear precursors e in good yields (72-96%) these were cyclized to the macrocycles f by a subsequent RCM. 

S. Ogawa, M. Ashiura, C. Uchida, S. Watanabe, C. Yamazaki, K. Yamagishi, and J. Inokuchi, Synthesis of potent p-D-glucocerebrosidase inhibitors W-Alkyl-p-valienamines, Bioorg. Med. Chem. Lett., 6 (1996) 929-932. 

W-alkyl- pyridinium tetraalkyl- ammonium tetraalkyl-phosphon ium trialkylsulfonium... 

The reaction of an w-alkyl(chloro)(dimethyl)silane or w-trialkylchlorosilane of the type RMe2SiX or R3SiX (X = Cl) with a hydrothermally activated silica represents the second and more popular approach. Excellent mass transfer characteristics with peptides can be... 

The reversed sense of diastereoselectivity is also observed in the direct Birch reduction alkylation of a number of ort/w-alkylated benzamides of 2-(methoxymethyl)pyrrolidine [i.e., l-(2-alkylbenzoyl)-2-(methoxymethyl)pyrrolidines, 8] which also give high diastereoselectivities of a-methylated products (see Table 6)33. Diastereomeric ratios (TR/TS) for the different R groups range from 5 95 for R = ethyl to 2 98 for R = 2-(tm-butyldimethylsilyloxy)ethyl33. 

From the archival enthalpies of formation of the other species, the enthalpy of formation of cyclohexyl methyl amine is —145.4 kJmoH. From equation 11, the enthalpy of formation of the corresponding salt is —501.2 kJmoH. Attempts to estimate an enthalpy of formation for A-methyldodecanamide reveals a paucity of data to work with, primarily for unsubstituted and A-methylamides . There is much enthalpy of formation data for w-alkyl carboxylic acids, including dodecanoic acid. The methylene increment... 

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