Methyl-oxazoline heterocycle

In NRPS, the cyclization domain catalyzes cyclization of the side-chain nucleophile from a dipeptide moiety such as AA-Ser or AA-Cys (AA = amino acids) to form a tetrahedral intermediate, followed by dehydration to form oxazolines and thiazolines (Scheme 7.1) [20]. The synthesis of a 2-methyl oxazoline from threonine follows a similar mechanism. Once a heterocycle is formed, it can be further modified by reductase to form tetrahydro thiazolidine in the case of pyochelin biosynthesis. Conversely, oxidation of the dehydroheterocycles lead to heteroaro-mahc thiazoles or oxazoles as in the case of epothilone D (Figure 7.2) [21]. 

Reports of [ 2 + 2] cycloaddition of nitrogen containing heterocycles to alkenes are so numerous that attention can be drawn here to only a few. Recent examples include the acetone-sensitized photoaddition of 4-oxazolin-2-one (248) to ethylene to give the cis-adduct 249,203 the photocycloadditions of N-substituted imidazoles to acrylonitrile204 and of N-methyl-4-hydroxy-quinol-2-one to cyclohexene,205 and the photoaddition of pentafluoro-pyridine to ethylene to give the 1 1- and 1 2-adducts 250 and 251,... 

A very recent paper by Saegusa, 7) describes a method of synthesizing polyoxyethylene macromonomers bearing a polymerizable heterocycle at the chain end. Here again the method involves initiation of the oxirane polymerization by means of an alcoholate (derived from 2-p-hydroxyphenyl)-oxazoline). As metalation agent butyllithium, was used since lithium alcoholates are not very reactive towards oxirane. Indeed, the macromonomers obtained exhibit very low degrees of polymerization. Deactivation was performed with methyl iodide ... 

Syntheses of the antibiotic compounds deoxynybomycin (100) and nybomycin (102) as well as related heterocyclic compounds have been described (Scheme 7). The 8-hydroxy-2-quinolone (97), readily prepared from o-anisidine in three steps, was converted into the fused oxazoline-quinoline derivative (98) by successive nitration, reaction with dibromomethane, and hydrogenation. Adaptation of the Doebner-von Miller quinoline synthesis to (98) provided the tetracyclic product (99), which upon methylation and oxidation gave deoxynybomycin (100) in 0.83% overall yield from o-anisidine. The key intermediate... 

Methyl-4-(1 -hydroxy-1 -methylethyl) benzene. See Tri methyl benzyl alcohol Methyl hydroxymethyl oleyl oxazoline CAS 14408-42-5 EINECS/ELINCS 238-387-5 Synonyms 2-(8-Heptadecenyl)-4-methyl-2-oxazol i ne-4-methanol 2-Oxazol i ne-4-methanol, 2-(8-heptadecenyl)-4-methyl-Classification Substituted heterocyclic compd. Empirical C22H41NO2 Uses Antistat in cosmetics... 

Fragmentations of heterocycles have played an important role in the preparation of amide derivatives. Moderate to good yields of a-hydroxy-amides were obtained on reaction of a-hydroxy-acid aceto-nides with primary amines.N-Alkyl-2-methyl-2-oxazolinium salts (obtained by mixing alkyl halides and 2-methyl-2-oxazoline in dichloromethane) were found to react with sodium benzeneselenolate to yield -(2-phenylselenoethyl)-t -alkylacetamides, which after oxidation to ] -vinyl analogues with sodium metaperiodate in methanol, gave secondary amides on sequential treatment with mercuric acetate in aqueous tetrahydrofuran and sodium borohydride/3M... 

An autoclave charged with 3-hydroxy-3-methyl-2-butanone, benzaldehyde, GaCla, and NH4GI, anhydrous NHg introduced with stirring until a pressure of 80 p.s.i.g. is obtained, then heated 4 hrs. at 90-100°/300-400 p.s.i.g. 2-phenyl-4,5,5-trimethyl-3-oxazoline. Y 96%. F. e. s. J. R. Gaines and G. R. Hansen, J. Heterocyclic Ghem. 96 (1964). 

Quaternization of the nitrogen atom in a heterocyclic system can activate the ring towards addition reactions. An oxazoline moiety was converted to an aldehyde in 97% overall yield by alkylation of oxazoline with MeOTf, reduction with sodium boro-hydride, and hydrolysis of the resulting aminal (eq 10). Alternatively, treatment of an TV-methylated oxazolium triflate with a Grignard reagent followed by aqueous acid produced a ketone. Reaction of alkenyl oxazoles with MeOTf induced spontaneous intramolecular [4 -i- 2] cycloaddition at room temperature leading to a hydroindole or a hydroisoquinoline after reduction by sodium borohydride (eq 11). ... 

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