Bicyclo[3.1.0]hexanes from sugar-derived diazo compounds and iodonium ylides. Diastereocontrol and synthetic applications

The CuI and Rh2(OAc)4 catalyzed decomposition of ethyl 2-diazo-4,5-isopropylidenedioxy-3-oxo-6-heptenoate results in intramolecular cyclopropanation products with opposite diastereoselectivity. In contrast, decomposition of the respective iodonium ylide can proceed without catalysts to give the cyclopropanation products with diastereoselectivity unchangeable by the presence of CuI and Rh2(OAc)4, revealing thus, that in this particular case the reaction is an electrophilic addition of the iodonium center to the double bond. The synthetic importance of these reactions has been demonstrated by preparing a number of precursors of cyclopentyl, cyclopropyl and bicyclo[3.1.0]hexyl antiviral carbocyclic nucleosides.