Dr. Alfred Hassner (when at the University of Colorado) found iodine azide (IN3), to add to terminal alkenes with complete anti stereoselectivity to the 2-butenes.
a. Draw the line and wedge structures of the products obtained on addition of iodine azide to both cis and trans-2-butenes. Assign ‘R' or ‘S' to the asymmetric centers in your product.
b. Propose a plausible mechanism (using curved arrow notation) for the addition of iodine azide to alkenes.