The developed method can be performed chemoselectively on activated alkenes over unactivated ones, as illustrated by the preferential formation of mono-chloroacylated product 140 in the β-chloroacylation of 4-vinyl allyl benzene A7 performed using 1 equivalent of benzoyl chloride B1 (Fig. ). As expected, when 3 equivalent of benzoyl chloride B1 was employed the di-chloroacylated product 141 was formed exclusively. Moreover, the dichloroacylated product 141 can be obtained by sequential reaction at the activated and unactivated double bonds as demonstrated in Fig. . The reaction of diene A8 proceeds in an 1,4-fashion delivering the product 142 in excellent diastereoselectivity (Fig. ). A radical trap experiment performed by adding radical scavenger 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), completely inhibited the reaction and produced the aroyl-TEMPO adduct 144 (Fig. ), supporting the formation of an aroyl radical. In agreement, employing the radical clock reagent β-pinene A9 under the standard conditions provided exclusively 143 through aroyl radical initiated ringopening followed by subsequent chlorine incorporation (Fig. ). The quantum yield of the standard reaction was measured to be 0.014, which indicates that an extended radical chain process is unlikely (see SI, Table ). UV/Vis absorption shifts of the binary mixture of photocatalyst Cu(dmp)(BINAP)BF4 and benzoyl chloride B1 before irradiation indicated coordination of ATRA reagent B1 to the photocatalyst (Fig. ). Stern-Volmer quenching experiments revealed that aroyl chloride B1 quenches excited Cu(dmp)(BINAP)BF4 species more efficiently than the alkene substrate A1 (Fig. ). Next, we analyzed the impact of excited-state lifetime and ligand environment of heteroleptic Cu(I)-photocatalysts. Besides the three heteroleptic Cu(I)-photocatalysts that were screened during optimization (cf. Fig. ), we additionally synthesized Cu(phen)(BINAP)BF4 (τ = 3 ns) and Cu(dmp)(DPEPhos)BF4 (τ = 14300 ns) with contrasting excitedstate lifetime values to compare their efficacy on the standard βchloroacylation reaction (Fig. ). The reduction potential of the catalysts is capable of reducing aroyl choride B1, but nevertheless gave different outcomes. The highest yield of 1 was obtained using Cu(dmp)(BINAP)BF4 catalyst having τ = 2188 ns. Intriguingly, when Cu(dmp)(DPEPhos)BF4 is used, the desired β-chloroketone 1 was obtained in 10% yield despite having a very high excited-state lifetime of 14300 ns. A similar trend was observed for Cu(dmp)(Xanthphos)BF4 (τ = 1133 ns). These results suggested that the presence of BINAP as a bidentate phosphorous ligand is crucial to the catalytic efficiency. However, Cu(phen)(BINAP)BF4 with an excited-state lifetime of only 3 ns provided the β-chloroketone 1 in 30% yield despite having BINAP ligand in its coordination sphere, which underscores the significance of both specialized ligand environment and longer excited-state lifetime of the Cu(I)-catalysts for the success of this photocatalytic method.