Resulting from Alkylation

Alkylation of cyclohexylidinephenylacetonitrile (89) with 2-chloroethyldimethylamine, using NaH as base, gives nitrile 90. Note that the product results from alkylation of the enolate which results in a double bond shift. This product (90) is transformed to unsaturated amine 91 on heating with HC1. 

Wei t al. (78) characterized mutations resulting from alkylation of a 10-base pair oligonucleotide with BPDE. Deletion mutations were the major mutational event detected. 

Methyl-l,2,4-triazole 37 undergoes radical alkylation to give monoalkylated 1-methyl-1,2,-4-triazoles 48a-e in which the new substituent is in the 5-position no addition products resulting from alkylation in the 3-position were observed (Equation 14 and Table 3) <2001TL7353>. 

We converted the alkoxyacetyl complexes 9 to the ethyl complex 8, by employing the aforementioned acyl ligand activation and BH reduction procedures, as outlined in Scheme 2. The a, -dialkoxyethylidene salts 9a, b resulted from alkylation of 6a,b with EtsO+PFg" in CH2CI2 recrystallization from CH2CI2-ether provided 9 in 72% yields as air-stable yellow PFg" salts. 

Mass spectra of OPEOs, their acidic metabolites, OPEC and halogenated derivatives in El and Cl modes have been reported [80-82]. The most prominent ions formed under Cl resulted from alkyl ion displacement and olefin displacement, and those formed under El resulted from benzylic cleavage [82]. 

Oximes at a carbon atom adjacent to an aromatic ring are more prone to produce mixtures of lactams. In some cases, the product resulting from alkyl migration becomes dominant. Some examples are shown below. 

The alkylations of the azaenolates are performed at —78 °C or below, and proceed exclusively at the C-terminus of the ambident azaally] anion. Asymmetric induction at —78 "C can be as effective as at —98 °C by slower addition of the electrophile to the azaenolate. Furthermore, higher optical yields2 result from alkylations in more dilute solutions at — 78 °C. 

Very few examples of electrophilic attack at sulfur(II) have been reported for these systems, with the exception of oxidation. Alkylation of the benzothiadiazine (88) with trimethyloxonium tetrafluoroborate gave a poor yield of the imino ether (89). The major product (90) resulted from alkylation at sulfur followed by hydrolytic ring opening of the resulting azasulfonium salt (79JCR(S)214). 

Studies using ESR spectroscopy have shown that the radical anions resulting from alkyl iodides and bromides are not stable and dissociative SET takes place, i.e. the cleavage of the aliphatic C—I and C—Br bonds is concerted with the SET. With aryl iodides and bromides, the radical anion does have a finite lifetime but then breaks down rapidly to aryl radicals. Evidence is required for each of the steps and, in particular, about whether radicals or... 

As is the case of non-silylated /V,A-di alkylaminoaceton itriles, the MSMA derivative has been alkylated with 5-bromopentene without any trace of a product that could result from alkylation of the a-trimethylsilyl- or the benzylic carbon atom.64... 

The adverse effects of PPO on noctuid larvae result from reduced bioavailability of amino acids caused by the covalent binding of oxidized chlorogenic acid to protein. When dietary protein (casein) was treated with PPO and chlorogenic acid, a substantial reduction in in vitro protein digestibility occurred. This reduction in digestibility may result from alkylation of lysine and/or protein cross-linking, which may impair the ability of the insect s trypsin to hydrolyze the protein. 

Hydrogenation of benzene over acidic catalysts or in the presence of acid results in the formation of the products resulting from alkylation by the intermediate cyclohexene such as cyclohexylbenzene, together with cyclohexane, as shown in Scheme 11.1. Slaugh and Leonard obtained cyclohexylbenzene in high selectivity in the hy-... 

An important question is Are the cytokinins present in tRNA incorporated intact into tRNA, in a manner like all other nucleoside triphosphates that are polymerized in the synthesis of tRNA, or does the presence of the cytokinins result from alkylation (transfer of isoprenoid side chain) of existing adenosine moieties already present in preformed tRNA In fact, experimental evidence has been reported for both processes (21,22). But the amounts of actual incorporation were very small, and the observed incorporation may be merely the result of transcriptional errors. Meanwhile, the evidence for cytokinin moieties in tRNA arising by alkylation of specific adenosine residues in preformed tRNA is conclusive (23). 

Alkyl compounds of transition metals are often kinetically instable, since they generally display lower activation energies for the decomposition routes, i.e., reduetion-elimination and/or / -H elimination, than the alkyl compounds of main group metals. With transition metal anodes, decomposition of the intermediary formed alkyl-metal complex therefore leads to the swift generation of disproportion and/or recombination products of the alkyl groups [121]. A diagram of these reactions is shown in Scheme 6, exemplified by the electrolysis of ethylaluminum compounds. Since the deeomposition reactions resulting from alkyl-metal interaction proceed at different rates for different transition metals, the dependence of the anodic reaction products on the type of metal is easy to understand. 

The oxidation of the two boron-sp- carbon bonds with trimethylamine A-oxide before the coupling (Scheme 2-28) solves the difficulty arising from protonolysis of the B-C bond and avoids contamination of the coupling product by side products resulting from alkyl group transfer [69, 70]. 

It is hoped that the foregoing examples provide an indication of the variety of outcomes, both good and bad, which can result from alkylations of this type of ip -carbanion, together with some useful methods for obtaining good yields. Many anionic species are not included in the discussion simply because their alkylation chemistry has not been reported, except sometimes with methyl iodide which, as discussed above, is not always a typical or representative electrophile in this typ>e of chemistry. 

With dibromoalkanes, the diethyl l,l-cycloalkyl-l-(ethoxycarbonyl)methylphosphonates are readily obtained by two successive alkylations in fair to good yields using NaH in THF-DMSO (Scheme 8.17), ° K2CO3 in MeCN-DMSO, NaOH (50%)/benzyl tributylammonium bromide or EtONa/EtOH, EtiO. By contrast, reaction of the potassium salt of diethyl 1-(ethoxycarbonyl)methylphosphonate with 1,3-dibromopropane leads to the formation of 1,2-oxaphosphorinane, resulting from alkylation at the methylene carbon and at phosphorus. ... 

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