Versatile and iodine atom-economic co-iodination of alkenes. 
Molecular iodine, I(2), is readily converted into 2 equiv of acetyl hypoiodite (CH(3)CO(2)I) via oxidation by (diacetoxyiodo)benzene (DAIB) followed by trapping of the iodide ion by acetoxyphenyl iodonium ion formed.  The in situ generated CH(3)CO(2)I is utilized for the synthesis of 1,2-iodo-cofunctionalized derivatives of a variety of alkenes.  Conversion of both iodine atoms of I(2) to I(+) sources results in 100% iodine atom economy for the reported iodo-cofunctionalization of alkenes.