A new, wide ranging, synthetically powerful, catalytic tandem cyclisation-anion capture process is proposed which depends on the rate of cyclisation of an organopalladium specifies (RPdX) onto a proximate alkene or diene being significantly faster than anion exchange and reductive elimination in the sequence RPdX → RPdY → RY + Pd(0). The catalytic cyclisation - anion capture sequence is illustrated
Alkyl- and π-allyl-palladium species arising from 5-exo-trig cyclisations onto proximate alkenes or dienes can be intercepted by hydride ion sources leading to carbo- and hetero-cyclic compounds usually in good yield.