Dialkyls with

Otherwise, the main reactions at the methylene group are the dialkylation with alkyl haUdes (77), the acetylation with acetyl chloride which yields acetylma1 ononitrile [1187-11-7] (78), the Knoevenagel condensation, as well as the condensation with triethyl orthoformate, gives... 

Reaction of beryllium dialkyls with an excess of alcohol yields the alkoxides Be OR)2. The methoxide and ethoxide are insoluble and... 

The 1,3-dianions formed across the sulfone of ) -ketosulfones may be selectively dialkylated with an a, co-dihalide and thus cyclize to give 2-ketothiane dioxides . Due to its polarity, the 2-keto-substituent (or other polar group in the 2-position) adopts the axial orientation (equation 124). 

Chiral hydroxy benzimidazole 267 was dialkylated with dibromomethane or benzaldehyde dimethyl acetal to form benzo[4,5]imidazo[l,2-f]oxazoles 268 and 269 (Equation 118) C1997TA1491, 1998TA2245>. After removal of the BOC group and formylation of the liberated amine, formylaminomethylthiazole cyclized in phosphoryl chloride to... 

Mono-2-alkylation of thianthrene with 2-chloropropanoic acid (74GEP2245940) and dialkylation with phenyltrichloromethane/AlCls (81EGP143901) have been claimed in the patent literature. The unusual 2,6-substitution pattern is claimed for chloromethoxymethylation using ClCH20Me/SnCl4(76IZV2799). 

The trialkyls also may be obtained by reaction of mercury dialkyls with indium ... 

Various diastereomeric di-, tri-, and tetrapeptides that carry the sterically demanding trifluoromethyl group instead of the natural a-proton at different positions within these short peptide sequences have been designed, and their stability towards enzymatic hydrolysis has been investigated. The structures of the a-trifluoromethyl (aTfm)-substituted amino acids are shown in Scheme 1. From these studies we gained valuable information on how a-trifluoromethyl-substi-tuted peptides may interact with proteins. The aTfm amino acids used in this study combine the conformational restrictions [49-52] of C -dialkylation with the unique stereoelectronic properties of the fluorine atom and have shown interesting effects on peptide-enzyme interactions [53,54]. 

In earlier sections it has been shown that the reaction of a magnesium dialkyl with one equivalent of a primary amine usually affords the primary amido derivative. However, it is also possible to effect elimination of the second equivalent of alkane to give magnesium imides. The reaction of MgEt2 with aniline in thf proceeded via an amido intermediate which eliminated ethane to yield the hexameric imido compound [ (thflMgNPhJg] which was the first homometallic magnesium imide to be structurally characterized. Equation (3.9). 

The bulky methylaluminoxane anion stabilizes the coordinatively unsaturated metal cation. Stabilization by noncoordinating anions such as carbosilane dendrimers is also viable.571 Aluminoxanes, however, are required to be used in large excess to be effective. Alternatively, the active catalyst can also be prepared by reacting a metal dialkyl with fluorinated boranes, borate salts or aluminate salts. 

Oxindol (64) reacts at position 3 to give dialkylation with 2 mol of alkyl halide and a cycloaddition with an a,[Pg.195]

The direct a-alkylation of monoketones normally employs reaction of an alkyl halide or sulfonate with the enolate anion produced using a strong base. This method can be satisfactorily used with symmetrical ketones, which are to be dialkylated with a dihalide, and with intramolecular cyclization reactions, where the formation of five- and six-membered rings is often favored over the formation of three-, four-, seven-, and eight-membered rings (M. Mous-seron, 1937 W.S. Johnson, 1963). Regioselective alkylation of dianions according to Hauser s rule (see p. 9f.) is usually also a satisfactory procedure (F.W. Sum, 1979). 

PRODUCTS OF MONO- AND DIALKYLATION WITH RELATIVE TOPICITY ula OF (S)-MALIC ESTERS THROUGH ALKOXIDE ENOLATES. THE RATIOS OF DIASTEREOMERS (SEE ds) WAS DETERMINED BY 3H or 13C NMR SPECTROSCOPY OR BY GC ANALYSIS. 

The sulfone moiety is a good acidifying group, so (methylsulfanyl)methyl sulfones 410 and 411 can be deprotonated and mono- or dialkylated with sodium hydroxide under PTC conditions or with sodium hydride619-622. The alkylated products can be easily hydrolyzed with hydrochloric acid in refluxing methanol, having been applied to the synthesis of acyclic and cyclic ketones. The acylation of compound 410 derived sodium anion has been performed with esters620. For the lithiation of a-thiosulfones 411622 and 412, n-BuLi, f-BuLi or LDA at —78 °C can be used. 

Continuing their work on 1,4-dianions of phenylhydrazone, Hauser and coworkers inspected similar reactions with the 1,4-oxime dianions98. Acetophenone oxime gave the dilithium salt in reaction with /-BuLi and underwent C-alkylation with benzyl chloride and dialkylation with 1,4-dibromobutane (equation 32). 

TV.V-Dialkylation, with or without hydroxylation on one of the alkyl groups, leads to loss of activity. 

Several methods have been recommended for the preparation of pure methylcopper, each having advantages over previously reported methods. Costa et al. consider the [Pb(CH3)4 + Cu(N03)2] method superior to the Grignard route, as reproducible analyses are obtained 82). However, Thiele and Kohler recommend the reaction of zinc dialkyls with cop-per(II) chloride in ether at — 78°C for the preparation of pure yellow methylcopper, red-brown ethylcopper, and orange propylcopper, uncontaminated by copper alkoxides (277). The mechanism was considered to be a reduction of copper(II) to copper(I) chloride, followed by the reaction of the latter with the zinc dialkyl. The results from the recent... 

Benzoylhydrazine reacts with ethyl acetoacetate at 130 °C in the absence of solvent to give first the pyrazolone (295 R = PhCO). Water from the reaction hydrolyzes the benzoyl group and a second molecule of the ester reacts to give the pyranopyrazolone (296) (63BSF2742). The aminopyrazolones (297) and carbon disulfide give the zwitterionic pyrazolothiazines (298) which S,5-dialkylate with diazomethane or alkyl iodides (78FES799). 

Rather similar hydrides of zinc, cadmium, beryllium and magnesium have been made by reducing their dialkyls with lithium aluminium hydride dissolved in ether ... 

The alkyls of Na, K, Rb, and Cs are colourless amorphous solids which are insoluble in all solvents except the liquid zinc dialkyls, with which they react to form compounds such as NaZn(C2Hs)3. The Li compounds are quite different, for they are soluble to varying extents in solvents such as benzene, in which they are polymeric, and both lithium methyl and ethyl exist as colourless crystalline solids at ordinary temperatures. 

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