Oxazoline primary amine

VibB as 79 for condensation with the primary amine of norspermidine 105 via the amide synthase VibH, resulting in unbound, soluble DHB-norspermidine 106 [128]. Two DHB-oxazoline monomers, still tethered as thioesters on VibF as 104, are then sequentially transferred to the primary and secondary amines of the DHB-norspermidine molecule to yield 107 and 66, respectively [124],... 

A-diphenylphosphinoyl imines also react with dialkylzinc in the presence of stoichiometric or catalytic amounts of different chiral (see Chiral) ligands (Scheme 24). Acid hydrolysis of the resulting phosphinamides occms without racemization and gives enantiomerically enriched primary amines. The allylation of various cyclic imines was obtained with high enantioselectivity (see Electrophile), 77 to 99% e.e., in the presence of lithiated bis-oxazoline ligands (Scheme 25). 

A two-step synthesis of 1,4-disubstituted imidazoles (8) from TOSMIC (1) plus an aldehyde, followed by reaction with ammonia or a primary amine, proceeds via a 4-tosyloxazoline (11). The reaction sequence could be classified as 1,2 and 1,5 bond formation, 1,5 bond formation, or transformation of another heterocycle. There are, however, analogies to the aldimine reactions, and so the process is detailed at this stage. Certainly the synthesis is carried out in two steps often with isolation of the oxazoline (see also Chapter 6). Heating (11) with a saturated solution of methanolic ammonia gives a 4-substituted imidazole with methanolic methylamine a 1,4-disubstituted product is isolated as a single regioisomer (Scheme 4.2.4). Some of the oxazolines cannot be isolated as they are unstable oils which have to be heated immediately with the amino compound [12]. Related is the synthesis of 2-carbamoyl-4-(2 -deoxy- 0-D-ribofuranosyl)imidazole [13]. 

Protection for primary amines. Sheehan and Guziec1 have introduced this reagent for replacement of both hydrogens of a primary amine function by incorporation into the very stable 4,5-diphenyl-4-oxazoline-2-one ring system (3).2 These Ox-protected derivatives are obtained by treatment of a primary amine or amino acid tetramethyl-ammonium salt with (1) in DMF. After stirring for 0.5 hr., the mixture is acidified (HC1) and extracted with ethyl acetate to obtain a diastereomeric mixture of hydroxy-oxazolidinoncs (2). The mixture is dehydrated to the Ox derivative (3) by trifluoroacetic acid (TFA). Ox derivatives are stable to aqueous base, refluxing ethanolic hydrazine,... 

Besides functional initiators, a wide range of functional terminating agents have been utilized for the preparation of functional poly(2-oxazoline)s, including deprotonated carboxylic acids [184, 185], amines [185, 186], and deprotonated thiols (Scheme 8.27) [187]. The termination with primary amines can be complicated by the formation of secondary amines that can react with a second polymer chain after proton transfer to the unreacted primary amines. 

Besides the formation of oxazole derivatives, Schollkopf and the others have successfully extended the a-alkali metalated isocyanides to the formation of the chain-extended primary amines, 2-oxazolines, 2-thiazoline-4-carboxylic esters," 2-imidazolines, 2-pyrrolines and pyrroles, thiazoles, 2-imidazolin-5-ones," 2-imidazolinones," etc. For example, a simple reaction between lithiomethyl isocyanide with two equivalents of piperonal followed by acetylation of the intermediate with acetic anhydride affords the corresponding oxazoline. ... 

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... 

The 4,5-diphenyl-4-oxazolin-2-one ring (469) is a good amine protecting group. It replaces both hydro ns of a primary amine, thus eliminating... 

Although there are numerous examples in the patent and scientific literature, this approach has been mainly used for the reactive toughening of polyamides. These chains are indeed end-capped by a primary amine, which is reactive towards polymers bearing maleic anhydride, acrylic acid, oxazoline, and epoxy pendant groups. 

In 2005 [61], Overman and coworkers described the application of their oxazoline system 41 to synthetically attractive trifluoroacetimidates 44 (Fig. 23) forming trifluoroacetamides 45, which, in contrast to benzamides 40, can be readily transferred into free primary allylic amines. 

Chemical Resolution of Compounds Containing Basic Groups. 3-Bromocamphor-8-sulfonic acid has been widely used as a resolving agent for compounds containing basic groups. A number of primary (1), secondary (2), and tertiary (3) amines as well as oxazolines (4) have been resolved by the formation of diastereomeric salts derived from 3-bromo-8-camphorsulfonic acid. 

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