I2-Promoted formal [3+2] cycloaddition of α-methylenyl isocyanides with methyl ketones: a route to 2,5-disubstituted oxazoles

An I-2-promoted formal [3+2] cycloaddition for access to oxazoles has been demonstrated. This is the first example of a Lewis acid-promoted formal [3+2] cycloaddition of isocyanides with methyl ketones involving the C equivalent to N cleavage of isocyanides. The salient feature of this approach is unconventional 2,5-disubstituted oxazole formation from isocyanides and ketones rather than 4,5-substituted oxazoline.