C- Alkylation derivs

Meyers lactams are widely used in synthesis of substituted synthons of interest and their functionalization is carried out under strong base conditions giving C-alkyl derivatives. Alkylation of bicyclic lactam 182 with electrophiles (alkyl, allyl, benzyl halides, chlorophosphonate), and a strong base (j-BuLi, LiHMDS, or KHMDS HMDS = hexamethyldisilazide) in THF at — 78 °C gave an endo-exo mixture of products where the major one is the rro/o-compound 183 in good yields. The ratios were determined by H NMR spectroscopy and are usually up to... 

Mannich reaction of 2-cyloalkyl(heteroaryl)-6-aryl-imidazo[2,l-A][l,3,4]thiadiazoles 161 with formaldehyde in the presence of cyclic bases (piperidine and pyrrolidine), in methanol with a catalytic amount of acetic acid, gives the corresponding C-alkylated derivatives 172 (Equation 8) <2006BMC3069>. 

The Williamson alkylation of benzoin and deoxybenzoin, using procedure 3.1.1.B, produces dialkoxystilbenes and alkoxystilbenes (>90%), respectively, together with lesser amounts of C,0-dialkylated and C-alkylated derivatives [18]. The yields are... 

Method F The haloalkane (0.25 mmol) is added to the Cr(CO),-complex of the phenyl-acetic ester (0.25 mmol) in CH2CI2 (5 ml) and CTA-Br (36 mg, 0.1 mmol) in aqueous NaOH (50%, 5 ml). The mixture is stirred at room temperature until the reaction is complete, as indicated by TLC analysis, and the organic phase is then separated, washed well with water, dried (Na2S04), and evaporated to yield the C-alkylated derivative (70-100%). 

Alkylation of P-dicarbonyl compounds and p-keto esters occurs preferentially on the carbon atom, whereas acylation produces the 0-acyl derivatives (see Chapter 3). There are indications that C- and 0-alkylated products are produced with simple haloalkanes and benzyl halides, but only C-alkylated derivatives are formed with propargyl and allyl halides [e.g. 90]. Di-C-alkylation frequently occurs and it has been reported that the use of tetra-alkylammonium 2-oxopyrrolidinyl salts are more effective catalysts (in place of aqueous sodium hydroxide and quaternary ammonium salt) for selective (-90%) mono-C-alkylation of p-dicarbonyl compounds [91]. 

Glycopyranosyl halides react with ethyl acetoacetate and pentan-2,4-dione under soliddiquid phase-transfer catalytic conditions, using potassium phosphate as the base, providing the C-alkylated derivatives (40-60%) ]94],... 

Because of the known detrimental effects of N-alkylation in isofagomine (61), Fan and coworkers prepared a range of C-alkyl derivatives such as compound 62 (Scheme 17), which constitute the most powerful inhibitors of (3-glucosidases known thus far.170... 

Pyrazolopyrimidine 148 reacted with magnesium to yield the corresponding Grignard reagent 149 that reacted with pivaldehyde to yield the corresponding C-alkylated derivative 150 (Scheme 5) <2003JOC2054>. 

C-alkyl derivatives (280) are obtained by direct addition of an alkyl halide at the end of the Dieckmann reaction, in benzene or xylene. O-Alkyl derivatives (281) are obtained by reacting sodium amide with ester 278, previously isolated, in benzene, followed by addition of the... 

Y. Ali and W. A. Szarek, Synthetic approaches to gem-di-C-alkyl derivatives of carbohydrates Nucleophilic addition reactions of 3-C-methylene compounds derived from l,2 5,6-di-0-isopropylidene-ot-D-rifto-hexofuranos-3-ulose using phase transfer catalysis, Carbohydr. Res. 67 Cll (1978). 

The synthesis of 6-C-alkyl derivatives of methyl a-isomaltoside for a study of the mechanism of hydrolysis by amyloglucosidase, U. Spohr,... 

On the other hand, the high reactivity of the aldehyde or potential aldehyde group enables many condensation reactions, leading to iV-alkylamino compounds (112) and analogous C-alkyl derivatives.359 361... 

C-Alkylated derivatives have shown immunostimulant properties, and 2-0- and -3-O-alkylated lipid-soluble derivatives are known to protect against the lipid peroxidation of biomembranes.250... 

A good route to 2-C-allyl (and hence by reduction, C-alkyl) derivatives of ascorbic acid involves the interaction of L-ascorbic acid with allyl acetates or allyl carbonates in the presence of Pd(0) catalyst.355... 

The first thallium(I) n complexes with carbollide ligands were synthesized by Stone et al. (180) addition of an aqueous solution of thallium(I) acetate to an aqueous alkaline solution of the dicarbaundecaborane anion, 7,8-CzB, , or its C-alkyl derivatives causes the formation of the new compounds (LIVa-c) [Eq. (15)]. One of the thallium atoms in the air-stable,... 

The aforementioned work thus provided the novel C3 C-alkylated derivatives 30 and 31, which selectivity inhibited a series of group 1 Nl sialidases compared to a group 2 N2 sialidase (Table 17.1) and bound group 1 N8 with the 150-loop in the open conformation [137], In particular, 31 gives a micromolar level of inhibition against pandemic 2009 Nl (09 Nl) sialidase. 

TABLE 17.1 Inhibition of Influenza A Virus Sialidases With C3 C-Alkylated Derivatives 30 and 31 [137]... 

Co(trien)(NH3)2] + has been isolated, and only the meso trans isomers (197-198) with two different axial ligands, remain to be distinguished. There is also an extensive chemistry of N and C-alkylated derivatives of (178 180) as cA-[Co(OH)(trien)(OH2)] assists the hydrolysis of amino acid esters, amino acid amides, and peptides to form cis-fi (194) and cA-jS2-[Co(OA0(trien)] + (195)(( A = amino acid) complexes. Chiral alkylated trien ligands have the potential for chiral stereospecificity in such reactions. 

Allyl phenyl ethers undergo an intramolecular [3,3]-sigmatropic rearrangement (the Claisen rearrangement) to form the C-alkyl derivative (Scheme 4.18). A consequence of the electrocyclic mechanisms is that the y-carbon atom of the allyl ether becomes attached to the aromatic ring. 

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