Palladium catalysis dehydrogenative coupling

A number of transition metal complexes will catalyze the dehydrogenative coupling of organotin tin hydrides, R SnI I, to give the distannanes, RjSnSnRj.443 These metals include palladium,449 gold,450, hafnium,451 yttrium, and ruthenium.452 The catalyst that is most commonly used is palladium, often as Pd(PPh3>4, and the most active catalysts appear to be the heterobimetallic Fe/Pd complexes, in which both metals are believed to be involved in the catalysis.443... 

Similar 1 1 and/or 1 2 coupling reactions of benzamides with alkynes were reported by Guimond s, Rovis s, and Li s groups [35]. Later, ruthenium- [36], palladium- [37], and nickel-catalyzed [38] versions for isoquinolinone synthesis were disclosed. Shi et al. reported similar lactam formation through dehydrogenative annu-lation of an indolecarboxamide 91 with 2c under palladium catalysis (Scheme 25.45) [39],... 

---