Reaction principle

Potassium permanganate or osmium tetroxide add to the less hindered side of the double bond of the alkene forming a cyclic intermediate. Addition of water destroys the ring and liberates the cis 1,2-diol. Initially, potassium permanganate loses one oxygen atom and is transformed into manganese dioxide while osmium tetroxide is reduced to osmic acid.

Examples

• With potassium permanganate

Fig.1

• With osmium tetroxide

Fig.2