Alkyl heterocycles

Cartxjxylalion and subsequent allylation of alkyl heterocycles (via Claisen rearrangement of allyl esters)... 

Naphthalene and other fused ring compounds are so reactive that they react with the catalyst, and therefore tend to give poor yields in Friedel-Crafts alkylation. Heterocyclic rings are also tend to be poor substrates for the reaction. Although some furans and thiophenes have been alkylated, a true alkylation of a pyridine or a quinoline has never been described.However, alkylation of pyridine and other nitrogen heterocycles can be accomplished by a free radical (14-23) and by a nucleophilic method (13-15). 

R = aryl, heteroaryl, alkyl R, R = aryl, alkyl, heterocyclic... 

This or the reverse order will give the observed product (135). Alkylation of piperazine 136 with 1-bromo-3-chloropropane gives the piperazine derivative 137 use of that intermediate to alkylate heterocycle... 

Ishii, Y. Okumura, K. Kobayashi, M., and Suzuki, M., Microorganism capable of degrading alkylated heterocyclic sulfur compound Patent No. JP11009293. 1999, Jan. 19. 

Microorganism capable of degrading alkylated heterocyclic sulfur compound [155],... 

R1 = H, alkyl, aryl R4 = aryl, alkyl, heterocycle E = ester, acyl, amide nitro... 

A number of S-, Se-, and Te-alkylated heterocyclic onium salts have been synthesized and their properties and reactivities reported [74JA7835 84M11 90HOU(E12b)676]. Until now, however, the corresponding per-... 

This hl-alkylated heterocycle (2) acts as the actual initiator because it is attacked rapidly under ring-opening by an oxazoline molecule, present in excess. The newly formed dimer (3) contains an ionic ring function, which is subjected to the same attack as the initiator molecule. The molecular weight of the polymers is controlled by the amount of the alkylating agent. Other suitable initiators for the polymerization of oxazolines are Lewis acids, protic acids, and alkyl chloroformates. 

The most important reactions of alkyl substituents a and y to the ring heteroatom are those which proceed via base-catalyzed deprotonation. Treatment of 2- and 4-alkyl heterocycles with strong bases such as sodamide and liquid ammonia, alkyllithiums, LDA, etc., results in an essentially quantitative deprotonation and formation of the corresponding carbanions. These then react normally with a wide range of electrophiles such as alkyl halides and tosylates, acyl halides, carbon dioxide, aldehydes, ketones, formal-dehyde/dimethylamine, etc., to give the expected condensation products. Typical examples of these transformations are shown in Scheme 17. Deprotonation of alkyl groups by the use of either aqueous or alcoholic bases can also be readily demonstrated by NMR spectroscopy, and while the amount of deprotonation under these conditions is normally very small, under the appropriate conditions condensations with electrophiles proceed normally (Scheme 18). 

As a result of 1,3-induction one expects that the main alkylation product will occur by attack of the electrophile from the opposite side to the R group on C-2, i.e., 8 from 6 and 10 from 7, with 8 and 10 being enantiomers. Hydrolysis of the alkylated heterocycles reestablishes the a-hydroxy acids which have been a-alkylated without racemization. Thus, the preparative value of this concept75-78 is dependent on two factors ... 

The first method is perhaps the most common, and is exemplified by the condensation shown in Scheme 3 of a 2-alkyl heterocyclic quaternary salt or the corresponding methylene base with a 2-hydroxy unsaturated aldehyde grouping (which usually is part of an aromatic ring, as in salicylaldehyde). These intermediates have given a broad assortment of spiropyran classes. The ready availability of 1.2.3.3.-tetraalkyl-3/f-indoleninium salts and salicylaldehydes has led to a large number of spiro-(2i/-l-benzopyran-2,2 -indolines) [this name will be used in preference to the correct T,3 -dihydrospiro(2//-l-bcnzopyran-2,2 -(2 //(-indole)]. A common acronym for this class, BIPS, will be used in this chapter as both singular and plural. 

A new approach for the synthesis of functionalized 4-alkylquinolines was developed utilizing electrogenerated carbanions <07SL1031>. The desired 4-alkylquinolines 83 were synthesized through a sequential alkylation/heterocyclization of p-(2-aminophenyl)-a,p-ynones 84 and the electrogenerated carbanions of nitroalkanes 85. This novel approach avoided metal and base catalysts and is performed under solvent free conditions. 

The simple photolytic or thermal decomposition of 0-acyl thiohydroxamates in benzene or pyridine as solvent yields the product of decarboxylative rearrangement, and not alkylbenzenes or alkylpyridines. However, photolysis in dichioromethane in the presence of protonated heteroaromatic bases results in the formation of alkylated heterocycles in good yield, as illustrated in equation (57). The great advantage of this latter method lies in the fact that the base to be alkylated is not used as the reaction solvent, which evidently permits the use of a much wider range of bases as trapping agents. 

The presence of alkylated heterocyclic nitrogen compounds in processed shale oil can cause sedimentation. This especially becomes problematic in... 

Trimethyl phosphate has been suggested as a convenient reagent for esterify-ing hindered carboxylic acids and was used in this manner to convert 1,1 -binaphthyl-8-carboxylic acid into its methyl ester. Trialkyl phosphates have also been investigated as reagents for alkylating heterocyclic nitrogen bases. ... 

More recently, it has been discovered that metallation of the alkyl heterocycle with a strong base such as Bu"Li followed by reaction of the intermediate anion with carbonyl compounds leads to the formation in high yields of adducts, which may either be isolated or subjected to chemical transformations (Schemes 35-37). -65... 

TV-Alkylated heterocyclic compounds can be built up in one operation by treating diol bissulfonates with primary amines. For instance, 1-cyclohexyl-piperidine, b.p. 234°, is obtained in 81% yield from 1,5-pentanediol bis-(benzenesulfonate) and cyclohexylamine, and 4-benzylmorpholine, b.p. 79°/ 2 mm, from 2,2 -oxybis(ethyl benzenesulfonate) and benzylamine.852... 

These products, in spite of their various chemical structures, all come from phosphorus chemistry. The first OPP, parathion, appeared on the market in 1944. They are phosphates, thiophosphates, dithiophosphates, phosphonates, etc., halogenated or not, alkylated, heterocyclic, etc. They affect the nervous system of pest insects by acting on cholinergic synapses to inhibit cholinesterase. 

Bromination of alkyl heterocycles with NBS can often give rise to substitution in the side-chain or the nucleus or both. When the reaction was applied to 1,7-dimethoxy-3-methylxanthone, the site of attack depended on the concentration of radical initiator the tendency to side-chain bromination increased with molar ratio of benzoyl peroxide. Reaction of manganese(III) acetate with... 

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