HETEROCYCLES VIA PD CATALYZED MOLECULAR QUEUING-PROCESSES - RELAY SWITCHES AND THE MAXIMIZATION OF MOLECULAR COMPLEXITY

Pd(O) catalysts facilitate the assembly of complex heterocycles and ca rbocycles containing 3 - 7 membered rings from a range of simple build ing blocks (allenes, carbon monoxide, alkenes, organometallic complexe s of B, Zn, Sn etc.). These cascade processes display remarkable chemo -, regio- and stereo-selectivity and considerably extend the scope and utility of our previously developed cyclisation-anion capture cascade s. The success of these processes is critically dependant on the relat ive rates of a range of potentially competing processes and the variou s substrates can be regarded as queuing for access to the catalytic me tal centre. Certain compounds are identified as relay switches because they extend the relay phase of the cyclisation-anion capture cascade whilst allowing the Pd catalysed cascades to switch between inter- and intra-molecular processes.