Cyeloadditions in the total synthesis of sporolide B

Closing rings: A recent total synthesis of sporolide B by the Nicolaou group is highlighted by two advantageous cycloadditions. Firstly, a regioselective [2+2+2] cycloaddition of highly elaborate substrates assembles the halogenated aromatic ring and subsequently an orthoquinone [4+2] cyclization closes stereoselectively the dioxane-containing macrocycle. These approaches should be considered in complex target syntheses.