Oxazoline N-oxides

Langlois synthesized (lS,5R)-44 by employing [3+2] cycloaddition between methyl methacrylate and camphor-derived oxazoline N-oxide (A) as the key-step (Scheme 66) [98]. 

Progress in the stereoselective syntheses of /1-lactams mediated by oxazoline N-oxides 00PAC1721. 

Chai, Q., Song, C., Sun, Z., Ma, Y., Ma, C., Daia, Y., and Andrus, M.B. (2005) Asymmetric allylation of aldehydes with allyltrichlorosilane using aza-paracyclophane-oxazoline-N-oxide catalysts. Te.trahe.dron Lett., 47, 8511-8615. 

Langlois Y. New Uses of Oxazolines, OxazoUne N-Oxides and DioxolanyUnms in Asymmetric Synthesis Curr. Org. Chem. 1998 2 1-18... 

In the other study [24], complexes containing heterocycles of a new type, namely, 2,3a-disubstituted 5,6-dihydro-3a//-[l,3]oxazolo[3,2-fe][l,2,4]oxadiazoles (6, Scheme 13.5), were prepared via the intermolecular platinum(II)-mediated DCA between coordinated nitriles in fran.y/aT-[PtCl2(R CN)2] and the oxazoline A-oxide C (Me)2CH20C(R )=N +(0 )(C -N ). With the exception of benzonitrile species, cycloaddition of oxazoline A-oxides to the platinum(II)-ligated nitriles proceeds diastereoselectively giving mixtures of enantiomers. The heterocyclic ligands in 6 were liberated by treatment with excess ethane-1,2-diamine [24]. 

The complex of Se(OTf)3 with new BINOL-derived ligands, bearing chiral bis-oxazoline at the 3,3 -carbons (BINOL-Box), was found to catalyze the 1,3-dipolar cycloaddition of N-benzylidenebenzylamine N-oxide to 3-((E)-2-butenoyl)-l,3-oxazolidin-2-one [139]. Using 6mol% of the most effective ligand and 5mol% of the Lewis acid, the corresponding endo-isoxazolidine was obtained as the major diastereoisomer with an endojexo ratio of 97/3, and the enantioselectivity of the endo product was 87%. 

In a similar vein, quinoline and isoquinoline N-oxides react with 2-oxazolin-5-ones (2) in the presence of acetic anhydride to give (3) which upon hydrolysis yield the aminomethyl derivatives (4). ... 

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