Abstract
[reaction: see text] Iridoid natural products 1-4 are accessed stereoselectively by means of tridentate (Schiff base)Cr(III)-catalyzed hetero-Diels-Alder reactions between ethyl vinyl ether and enantioenriched 5-methyl-1-cyclopentene-1-carboxaldehyde. An efficient route to the aldehyde from citronellal is afforded by the ring-closing metathesis reaction.