As for 1,3-enynes 6a and 8a, we reasoned that site-selectivity can be attributed to the steric interaction during the arylative crosscoupling step. Specifically, in the case of 4-phenyl 1,3-enyne 6a, the propargylic radical 6a-A is sterically less encumbered and is thus prone to undergo arylative cross-coupling at the propargylic position to produce 1,2-adduct 7a. In contrast, as for 4-alkyl 2phenyl-1,3-enyne 8a, the addition of cyanoalkyl radical 2a-B to its double bond affords a pair of resonance structures, the tertiary propargylic radical 8a-A and allenyl radical 8a-B. The allenyl radical 8a-B is more prone to undergo arylative cross-coupling than its resonance form, tertiary benzylic radical 8a-A. Moreover, the 1,4-adduct allene 10k was calculated to be significantly more stable than the 1,2-adduct 10k' by 12.4 kcal/mol due to strong conjugation of allene with both aryl groups (Figure ). Remarkably, the readily accessible chiral copper catalyst works not only as photoredox catalyst for radical formation, but also as the source of stereoinduction in C(sp 3 )-C(sp 2 ) and C(sp 2 )-C(sp 2 ) bond-formations. As such, these cross-coupling processes are redox-neutral, and do not require external strong base to activate the boronic acids.