Regio- and stereoselective 1,3-dipolar cycloaddition reactions between arylideneacetones and stabilized azomethine ylides obtained from ninhydrin and indenoquinoxalinones
Stabilized azomethine ylides, generated in situ from proline/sarcosine and ninhydrin or indenoquinoxalinones, underwent 1,3-dipolar cycloaddition at the activated double bond of arylideneacetones, leading predominantly to endo-spiro adducts. These products formed as a result of addition between the less substituted carbon atom of azomethine ylide and the most electrophilic site of the dipolarophile.