,-unsaturated acylammonium 
 salts , generated in situ from commodity acid chlorides 
 and a chiral isothiourea 
 organocatalyst , comprise a new and versatile family of chiral 
 dienophiles for the venerable diels  alder ( da ) cycloaddition . 
 their reactivity is unveiled through a highly diastereo- and enantioselective 
 diels  alder / lactonization organocascade that generates cis- and trans - fused bicyclic - 
 and -lactones bearing up to four contiguous stereocenters . 
 moreover , the first examples of da - initiated , stereodivergent 
 organocascades are described delivering complex scaffolds found 
 in bioactive compounds . 
 the origins of stereoselectivity are 
 rationalized through computational studies . 
 in addition , the utility 
 of this methodology is demonstrated through a concise approach to 
 the core structure of glaciolide and formal syntheses of fraxinellone , 
 trisporic acids , and trisporols .