Oxazolium 5-hydroxy-, cycloaddition

Oxazolium hydroxide, anhydro-2-m-bromophenyl-5-hydroxy-3-methyl-4-trifluoroacetyl-X-ray structure, 6, 180 Oxazolium hydroxide, anhydro-4-hydroxy-cycloaddition reactions, 6, 208 IR spectra, 6, 186 mesoionic structures, 6, 179 tautomerism, 6, 185 reactions, 6, 206-211 synthesis, 6, 225... 

Oxazolium hydroxide, anhydro-5-hydroxy-aromaticity, 6, 184 cycloaddition reactions, 6, 209 dimerization, 6, 207 1,3-dipolar cycloaddition reactions with alkynes, 6, 210 electrophilic reactions, 6, 207 mesoionic reactions, 6, 188 reactions, 6, 206-211 synthesis, 6, 225-227... 

The photocycloaddition of aliphatic and aromatic aldehydes with 2,4,5-trimethyloxazole (131) gave bicyclic oxetanes 132 in almost quantitative yields hydrolitic cleavage led selectively to erytro a-amino-P-hydroxy methyl ketones 133 <00CC589>. The oxazolium salt 134 was converted to the azomethine ylide 136 via electrocyclic ring opening of the oxazoline 135. Intramolecular cycloaddition afforded 137 in 66% overall yield which was transformed into the aziridinomitosene derivative 138 . 

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