Synthesis of allenes has been achieved by using palladium-catalyzed hydrogen-transfer reactions. Various propargylic amines, which were readily prepapred from iodobenzenes and propargylic amines by Sonogashira coupling reaction, underwent the hydrogen-transfer reaction in the presence of Pd2dba3.CHCl3/(C6F5)3P catalyst at 100 degrees C in dioxane for 24 h, giving the corresponding allenes in 43-99% yields. Various propargylic alcohols containing a propargylic aminomethyl group, synthesized by the addition of lithium acetylides of N,N-diisopropylprop-2-ynylamine to aldehydes and a ketone, also underwent the hydrogen-transfer reaction in the presence of Pd2dba3.CHCl3 catalyst and (C6F5)3P at 80 degrees C in dioxane, giving the corresponding allenes in 56-92% yields. In the current transformation, propargylic amines can be handled as an allenyl anion equivalent and introduced into various electrophiles to be transformed into allenes under palladium-catalyzed conditions.

[reaction: see text] Propargylic diisopropylamines containing heterocycles, which were prepared readily from heterocyclic bromides and propargyldiisopropylamine by the Sonogashira coupling reaction, underwent the allene transformation reaction in the presence of Pd(2)(dba)(3).CHCl(3) catalyst (2.5 mol %) and 1,2-bis[bis(pentafluorophenyl)phosphino]ethane (10 mol %) at 100 degrees C in CHCl(3), giving the corresponding heterocyclic allenes in good to high yields via the palladium-catalyzed hydride-transfer reaction.

Mono- and 1,3-disubstituted allenes were synthesized from the corresponding propargylamines via palladium-catalysed hydride-transfer reaction. In the current transformation, propargylic amines can be handled as allenyl anion equivalents and introduced into various electrophiles to be transformed into allenes under palladium-catalyzed conditions.

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