Alkylating reagent

A versatile tryptophan synthesis which proceeds directly from indoles as starting materials was developed by Gilchrist[5], The alkylation reagent is the... 

A iridine traces in aqueous solution can be determined by reaction with 4-(p-nitroben25l)pyridine [1083-48-3] and potassium carbonate [584-08-7]. Quantitative determination is carried out by photometric measurement of the absorption of the blue dye formed (367,368). Alkylating reagents interfere in the determination. A iridine traces in the air can be detected discontinuously by absorption in Folin s reagent (l,2-naphthoquinone-4-sulfonate) [2066-93-5] (369,370) with subsequent chloroform extraction and hplc analysis of the red dye formed (371,372). The detection limit is ca 0.1 ppm. Nitrogen-specific thermal ionisation detectors can be used for continuous monitoring of the ambient air. 

Phosphorus—hydrogen compounds undergo a metathetical exchange with some organometallic alkylating reagents (see Grignard reactions) ... 

Primary and secondary amines are usually converted to tertiary amines using formaldehyde and hydrogen in the presence of a catalyst (eqs. 5 and 6). This process, known as reductive alkylation (222), is attractive commercially. The desired amines are produced in high yields and without significant by-product formation. Quatemization by reaction of an appropriate alkylating reagent then follows. 

Excess alkylating reagent is required if the tetraorganotin is desired as the exclusive product. In commercial practice, the stoichiometry is kept at or below 4 1, since the cmde product is usually redistributed to lower organotin chlorides in a subsequent step and an ether is used as the solvent (86). The use of diethyl ether in the Grignard reaction has been generally replaced with tetrahydrofuran. 

The alkah metal xanthates react readily with the various alkylating reagents to form the testers ... 

The principal electrophiles to attack ring sulfur are either oxidants or alkylating reagents. Thiophene sulfoxide and sulfone formation is discussed in Section 3.02.2.6. Alkylating agents capable of forming thiophenium salts include trimethyloxonium tetrafluoroborate (MeaO BF ) and alkyl fluorosulfonates (ROSO2F). The salts e.g. 87) are conveniently isolated as hexafluorophosphates (88). 

Such compounds contain two or three pyridine-like heteroatoms. For the symmetrical systems (73) and (74), no ambiguity occurs, but for systems (75)-(78) there are at least two alternative reaction sites. It appears that reaction takes place at the nitrogen atom furthest away from the pyrrole-like heteroatom, as shown in (75)-(77) where evidence is available from reactions with alkylating reagents (Section 4.02.1.3.8). 

The leaving group in the alkylating reagent has a major effect on whether C- or O-alkylation occurs. In the case of the lithium enolate of acetophenone, for example, C-alkylation is predominant with methyl iodide, but C- and O-alkylation occur to approximately equal extents with dimethyl sulfate. The C- versus O-alkylation ratio has also been studied for the potassium salt of ethyl acetoacetate as a function of both solvent and leaving group. ... 

A vast variety of perfluoroalkanesulfonic esters are known, and their application in synthetic organic chemistry is increasing rapidly (for a comprehensive review, see reference 66) These compounds are readily available by the reaction of organic halides with silver perfluoroalkanesulfonate or by the reaction of an alcohol with the corresponding perfluoroalkanesulfonic anhydride or chloride Alkyl per-fluoroalkanesulfonates are powerful alkylating reagents because of the excellent... 

Another triflate ester that recently has found growing application in organic synthesis is commercially available trimethylsilylmethyl trifluoromethanesul fonate. This powerful alkylating reagent can be used for the synthesis of various methylides by an alkylation-desilylation sequence A representative example is the generation and subsequent trapping by 1,3-dipolar cycloaddition of indolium methanides from the corresponding indole derivatives and trimethylsilylmethyl trifluoromethanesulfonate [108] (equation 54)... 

Those derivatives that result by the action of acylating and alkylating reagents, such as A -acetylcotarnine (9b), A-benzoylcotarnine (9c), or cotarnmethin methyliodide (19) can only be derived from... 

Relative rates of alkylation of toluene and benzene using a mixture of nitro-sonium hexafluorophosphate, nitromethane (or acetonitrile) and aliphatic amine as the alkylations agent have been determined at 25 °C as follows360 1.5 (ethyl-amine), 2.5 (i-propylamine) and 3.5 (benzylamine) nothing more as yet is known about the kinetics of alkylation with these new alkylating reagents. 

Since the mid-1960s C10/13 /z-paraffins have been used as the starting material for the manufacture of the corresponding C10/13 n-olefin (required as alkylation reagent in the manufacture of LAB, e.g., Hiils, Pacol process). 

In terms of the production of olefins suitable for use as alkylation reagents in the synthesis of LAB, the Olex part of the process is of low priority. The olefins produced here are used mainly in the manufacture of oxoalcohols. The separation of the olefins from the paraffins proceeds by the same technology as that developed for the Molex process with the difference being that the sepa-... 

Burgess followed a similar strategy for the preparation of the salts 8 (Scheme 7). On that occasion several routes to mono-N-substituted imidazoles were explored yielding the desired compoimds in variable yields depending on the nature of the amines. The chirality was introduced via alkylating reagents 9 bearing chiral oxazolines [15]. 

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