1,3‐Diethynylallenes: New Modules for Three‐Dimensional Acetylenic Scaffolding.

Regioselective Pd0 -catalyzed cross-coupling of bispropargylic precursors 1 with silyl-protected alkynes gave rise to the first 1,3-diethynylallenes 2 [Eq. (1), LG=leaving group]. In enantiomerically pure form, these novel carbon-rich modules could provide access-by oxidative oligomerization-to a fascinating new class of helical oligomers and polymers.