L- alkyl

While both 2- and 3-vinylindole have been synthesized and characterized[l,2], they arc quite reactive and susceptible to polymerization. This is also true for simple l-alkyl derivatives which readily undergo acid-catalysed dimerization and polymerization[3]. For this reason, except for certain cases where in situ generation of the vinylindoles is practical, most synthetic applications of vinylindoles involve derivatives stabilized by EW-nitrogen substituents[4]. 

Alkylation of bis(4-methyl-2-thiazolyl)urea (257) with dimethyl sulfate gives product 258 dimethylated on the ring nitrogens (Scheme 154) (488). Alkylation of l-alkyl-3-(2-thiazolyl)urea from its derived anion formed by NaH gives 259 (Scheme 155). 

The infrared spectra of a set of 2-thiazolylthioureas are reported in Ref. 486. The ultraviolet spectra of l-aryl-3-(2-thiazolyl)thioureas are characterized by two bands of approximate equal intensity around 282 and 332 nm (492). For l-alkyl-3-(2-thiazolyl)thioureas these bands are shifted to 255 and 291 nm, respectively (492). The shape of the spectrum is modified further when l.l -dialkyl-3-(2-thiazolyl)thioureas are considered (491). Fragmentation patterns of various 2-thiazolylthioureas have been investigated (100, 493), some of which are shown in Scheme 158. Paper and thin-layer chromatography provide an effective tool for the analysis of these heterocyclic thioureas (494. 495). 

Reportedly, simple alkyl isocyanates do not dimerize upon standing. They trimerize to isocyanurates under comparable reaction conditions (57). Aliphatic isocyanate dimers can, however, be synthesized via the phosgenation of A[,A[-disubstituted ureas to yield /V-(ch1orocarhony1)ch1oroformamidine iatermediates which are subsequendy converted by partial hydrolysis and base catalyzed cycUzation. This is also the method of choice for the synthesis of l-alkyl-3-aryl-l,3-diazetidiones (mixed dimers of aromatic and aUphatic isocyanates) (58). 

Isoquinoline also forms Reissert compounds when treated with benzoyl chloride and alkyl cyanide (28), especially under phase-transfer conditions (29). The W-phenylsulfonyl Reissert has been converted to 1-cyanoisoquinoline with sodium borohydride under mild conditions (154). When the AJ-benzoyl-l-alkyl derivative is used, reductive fission occurs and the 1-alkyLisoquinoline is obtained. 

Imidazole-4,5-dicarboxylic acids, coupling, 5, 403 decarboxylation, 5, 434 1-substituted synthesis, 5, 468 synthesis, 5, 362, 402, 484 Imidazole-4,5-dione, l-alkyl-2-phenyl-synthesis, 5, 129, 479 Imidazole-2,4-diones tautomerism, 5, 370 Imidazole-4,5-diones tautomerism, 5, 370 Imidazole-2,4-dithione, 5,5-diphenyl-tautomerism, 5, 370 Imidazole-2,4-dithiones tautomerism, 5, 370 Imidazolepropanol synthesis, 5, 486 Imidazoles accelerators epoxy resins, 1, 407... 

Imidazole-5-thione, 4,4-diphenyl-tautomerism, 5, 368 3 H-Imidazole-2-thione, 1,3-dimethyl-structure, 5, 367 Imidazole-2-thiones acidity, 5, 367 betaines, 5, 372 synthesis, 5, 481 tautomerism, 5, 367 3H-Imidazole-2-thiones synthesis, 5, 473, 6, 992 Imidazolides deacylation, 5, 453 mass spectra, 5, 360 phosphoric acid reactions, 5, 454 reactions, 5, 451-453 Imidazolidine, l-alkyl-3-phenyl-N-oxidation, 5, 427 Imidazolidine, 1,3-benzyl-2-phenyl-oxidation, S, 427... 

A kinetic study of the mercuric acetate oxidation of l-alkyl-3,5-dimethyl-piperidines (81) and 3-alkyl-3-azabicyclo[3.3.1]nonanes (82) was made to evaluate the effect of the N-alkyl group on the rate of oxidation and to contrast these two ring systems (70). The maximum factor in the piperidine... 

The treatment of esters of aromatic acids with l-alkyl-2-pyrrolidones and l-alkyl-2-piperidones is an extremely useful method for the preparation of simple pyrrolines and piperideines, respectively. The l-alkyl-3-aroyl-2-... 

Acetyl-CoA l-alkyl-2-lysoglycero-y pho.sphocholine tran.sferase... 

Further alkylation of the anhydro-bases derived, by treatment with strong base, from quaternary 1-alkyl-a-, 2-alkyl-j8-, 2-alkyl-y-, and l-alkyl-8-carbolinium salts takes place at the indole nitrogen which in the anhydro-bases is a center of high electron density (see Section VI). 

The reactivity of the 1-methyl group and of corresponding positions (i.e., a-carbon atoms) in other l-alkyl-j8-carbolines, analogous to that in a-picoline, quinaldine, and isoquinaldine, is due to the acidity of this center. Deprotonation yields a resonance-stabilized anion (288) which reacts readily with electrophilic reagents. Metallation with phenyl-lithium of the 1-methyl group of a l-methyl-j8-carboline derivative in which the indole nitrogen is protected, first described by Woodward... 

Tire and NMR parameters of some 1-alkyl-4-benzimidazolyl-2-idene- (type 72) and l-alkyl-4-(5-methylpyrazolyl-3-idene)-l,4-dihydro pyridines (type 73) were discussed in 89CC1086 and 91JOC4223. Comparison of the shifts for DMSO-dg and CDCI3 solutions with data reported for quaternary pyridinium compounds as well as anionic species in the azole series and data obtained for mesoionic betaines of the azinium azolate class left no doubt that these heterofulvalenes have a betaine character and, therefore, the NMR signals correspond to their dipolar resonance form. 

Similarly, a number of l-alkyl(aryl)-4-ehloro-3-nitro-l,8-naphthyridin-2 (IH)-ones (100) have been reported to reaet with ammonia or alkylamines to afford the eorresponding 4-amino eompounds [101, R = H, CH3, C2H5, CH(CH3)2, CH2 CfiHs] (91JHC2029, 91MI2 92JMC4866). 

Boiled in a water-dioxane solution in the presence of acids, these compounds turn into l-alkyl-3-propynyl-5-methylpyrazoles (Scheme 25). 

In the reactions of nucleophilic addition to diacetylene, monoalkylhydrazines behave in two ways (71AKZ743). In an anhydrous medium at 40-50°C, the reaction with methyl- and ethylhydrazines proceeds in such a way that a more nucleophilic disubstituted nitrogen atom attacks the terminal carbon atom of diacetylene to form l-alkyl-3-methylpyrazoles (17), the content of isomeric 1-alkyl-5-methylpyrazoles being 15% according to GLC (71AKZ743 73DIS 77AKZ332). 

In aqueous solutions, the prevailing process is the primary attack of the unsubstituted nitrogen atom of alkylhydrazines at the terminal carbon atom of diacetylene with predominant formation of l-alkyl-5-methylpyrazoles (18) (73DIS). The content of isomeric l-alkyl-3-methylpyrazoles is less than 10% (GLC). In the authors opinion, this different direction of the attack at diacetylene in aqueous media is related to the hydration of alkylhydrazines and the formation of ammonium base RN" H2(0H) NH2, in which the primary amino group becomes the major nucleophilic center. 

Diacetylenic lotsitch reagents with azides (THF, 15-18°C, 20 h) afford l-alkyl(aryl)-5-ethynyl-l,2,3-triazoles (94) in 48-70% yield(67ZOR2241). These... 

A diastereomeric mixture of l-alkyl-7-(]-alkylperhydropyrido[l,2-u]-pyrimidin-6-yl)-],2,3,4,8,9-hexahydro-9u-pyrido[],2-u]pyrimidines 412 was obtained in the reaction of glutaraldehyde and A-alkyl-1,3-propanediamines in the presence of a drop of AcOH at 0 °C, then at ambient temperature for 13 h (96H(43)2487). 

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