Tandem reactions allenic substrates

In addition to the 1,3-dienes, in situ formed allenes were applied as substrates and cyclized with 2-iodophenols as well. In 2007, Liang and co-workers reported a novel palladium-catalyzed intermolecular tandem reaction for the synthesis of tetracyclic compounds from propargylic compounds and 2-iodophenols. The corresponding tetracyclic compounds were isolated in moderate to good yields (Scheme 2.47). In respect of the reaction pathway, the possible reaction intermediate was isolated and applied. In detail, this transformation consists of two catalytic cycles. The steps are (a) initial decarboxylation of propargylic compound by palladium(O) to... 

Allenic esters react as enoates in tandem difunctionalization reactions using organocopper reagents as Michael donors (J.-y-unsaturated esters result (equation 28).81 These substrates have found application in the synthesis of a variety of heterocyclic systems.114... 

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