A synthesis of an ionomycin calcium complex.

Caught in the middle: The ionomycin calcium complex (see structure; O red, Ca green) was the target of an approach featuring the efficient asymmetric synthesis of an allene by a copper(I)-mediated anti-selective S(N)2' reaction, a highly stereoselective gold(III)-catalyzed cycloisomerization of an alpha-hydroxyallene, and a Rh-catalyzed rearrangement of an alpha-diazo-beta-hydroxyketone.