Pseudo-pteroxazole

Corey s retrosynthetic concept (Scheme 9) is based on two key transformations a cationic cyclization and an intramolecular Diels-Alder (IMDA) reaction. Thus, cationic cychzation of diene 50 would give a precursor 49 for epf-pseudo-pteroxazole (48), which could be converted into 49 via nitration and oxazole formation. Compound 50 would be obtained by deamination of compound 51 and subsequent Wittig chain elongation. A stereocontroUed IMDA reaction of quinone imide 52 would dehver the decaline core of 51. IMDA precursor 52 should be accessible by amide couphng of diene acid 54 and aminophenol 53 followed by oxidative generation of the quinone imide 52 [28]. 

Oxazoles are known in natural products and also find wide incorporation into synthetic medicinal compounds. Oxazoles can be found in the natural products (-)-hennoxazole A (antiviral) and leucascandrolide A (cytotoxic and antifungal). Benzoxazoles and isoxazoles are less common in natural products. Pseudo-pteroxazole (benzoxazole-containing anti-tubercular agent) and ibotenic acid (isoxazole-containing neurotoxin) are two examples. 

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See also in sourсe #XX -- [ ]

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