Remarkable switch of regioselectivity in Diels-Alder reaction: divergent total synthesis of borreverine, caulindoles, and flinderoles.Switchable reaction patterns of dimerization of indole substituted butadienes via a Lewis acid and thermal activation are reported.  While under acidic conditions dimerization occurred around the internal double bond of the dienophile, a complete switch of regioselectivity was observed under thermal conditions, where dimerization occurred around the terminal double bond of the dienophile. 
THERM
Remarkable switch of regioselectivity in Diels-Alder reaction: divergent total synthesis of borreverine, caulindoles, and flinderoles.Switchable reaction patterns of dimerization of indole substituted butadienes via a Lewis acid and thermal activation are reported.  While under acidic conditions dimerization occurred around the internal double bond of the dienophile, a complete switch of regioselectivity was observed under thermal conditions, where dimerization occurred around the terminal double bond of the dienophile. 
THERM