**4. Metal-catalyzed C-N bond formations**

#### **4.1 Ru-catalyzed C-N bond formations**

Several methodologies have been developed for various difunctionalizations of which transition-metal based photocatalytic C-N bond formations is in high demand. Dagousset *et al.* in 2014 reported a metal-catalyzed azido- and aminotrifluoromethylation of alkenes (**2**) from alkene (**1**), azidotrimethylsilane and Umemoto's reagent (**Figure 5**) [9]. The radical-mediated difunctionalization of alkene is promoted under the irradiations of blue LEDs in the presence of a Rucatalyst. According to the proposed reaction mechanism in the presence of visible light the catalyst Ru(bpy)3 2+ form an excites species [Ru(bpy)3 2+] \*which generates the CF3 radical via a single electron transfer (SET) from Umemoto's reagent. The CF3 radical reacts with the alkene (**1**) providing the radical species with subsequent oxidation to a cation via a SET process from [Ru(bpy)3 3+]. Finally, the nucleophilic addition of this β-trifluoromethylated carbocation by TMSN3 or amine afforded the corresponding trifluoro methylated product (**2**).

Yasu *et al.* in 2013 reported a metal-catalyzed facile intermolecular aminotrifluoromethylation of alkenes (**Figure 6**) [10]. This is a highly efficient bifunctional reaction taking place between alkene (**3**), and Umemoto's reagent in MeCN. Here MeCN acts as a *N*-nucleophile, known as an aminative carbocation trap agent (Ritter-type reaction) and Umemoto's reagent serving as the CF3 source. The reaction takes place via initial SET processes in the presence of blue LEDs through excitation of [Ru(bpy)3] 2+ to \*[Ru(bpy)3] 2+ which reduce the Umemoto's reagent to produce a CF3 radical. Then this CF3 radical attacks alkene (**3**) to give a radical which is further oxidized by [Ru(bpy)3] 3+ to form a trifluoromethylated carbocation through another SET process. Finally, the additions of RCN, to the

**Figure 5.** *Synthesis of azido and Aminotrifluoromethylated products.*

*Construction of C-N Bond* via *Visible-Light-Mediated Difunctionalization of Alkenes DOI: http://dx.doi.org/10.5772/intechopen.98949*

**Figure 6.** *Synthesis of Aminotrifluoromethylation derivative.*

carbocation followed by hydrolysis (Ritter type amination) form the final aminotrifluoromethylated product (**4**).

Carboni *et al.* in 2014 demonstrated an elegant visible-light-mediated method for the synthesis of carbotrifluoromethylation (**6**) of enecarbamates using Togni's reagent as the CF3 source and NaN3 as the nucleophile (**Figure 7**) [11]. Herein, the CF3 radical is generated from the Togni reagent via a reductive photo redox path under a single electron transfer process. Then the addition of enecarbamates (**5**) generates α-amido radical which is rapidly oxidized to an acyliminium cation by a SET process. Finally, nucleophilic additions of NaN3 affords the product (**6**).

Bearing the importance of C-N bonds in mind Yang *et al*. in 2020 developed an efficient alkylazidation (**8**) using alkene (**7**), sodium azide and heteroareniumsalts as functionalized alkyl reagents for the synthesis of 2-azido-1-(1,4-dihydropyridin-4-yl)-ethane's (**8**). This reaction permits the incorporation of both azido and 1,4 dihydropyridin-4-yl group via difunctionalization of alkenes to construct C-C and C-N bonds in a single operation (**Figure 8**) [12]. The [Ru(bpy)3] 2+ specie is excited to [Ru(bpy)3] 2+\* by irradiated it with visible-light and undergoes single-electron transfer (SET) with NaN3 to form an azido radical (N3). The addition of azido radical across the C=C bond of alkene (**7**) generates an alkyl radical which is followed by the addition of the pyridinyl ring of pyridinium and finally, reductions by the [Ru(bpy)3] <sup>+</sup> species gives a product (**8**) and regenerates the active catalyst.

Yu *et al*. in 2016 disclose a Ru-catalyzed visible-light-mediated synthesis of azotrifluoromethylation (**10**) in the presence of alkenes (**9**) with aryldiazonium salts and sodium trifluoromethanesulfinate (**Figure 9**) [13]. This reaction is successful for unactivated alkene. Both electron-donating and electron-withdrawing groups of alkene and aryldiazonium salts give their product (**10**) in good yields. These trifluoromethylated azo products are useful building blocks for many heterocycles and nitrogen-containing compounds. As per the suggested mechanism in (**Figure 9**) in the presence of blue light, photoexcitation of the photocatalyst

**Figure 7.** *Synthesis of Carbotrifluoromethylation derivative.*

**Figure 8.** *Synthesis of 2-Azido-1-(1,4-dihydropyridin-4-yl)-ethanes.*

**Figure 9.** *Synthesis of Trifluoromethylated azo compounds.*

[Ru(bpy)3] 2+ generates the excited state \*[Ru(bpy)3] 2+ species. This active species is transferred into the oxidizing photocatalyst [Ru(bpy)3] 3+ via SET oxidation by the phenyldiazonium salt. This active species serves as a strong oxidant to oxidize Langlois' reagent to produce CF3 radical upon removal of SO2 and returning the photocatalyst to its ground state. At this time, the CF3 radical undergoes addition to the alkene (**9**) to generate the radical intermediate (A), which is easily trapped by the aryldiazonium salt to give the radical cation intermediate (B). Similarly, another SET reduction of intermediate (B) by the reducing \*[Ru(bpy)3] 2+ species gives to the desired product (**10**).

Since vicinal diamine are found in many pharmaceuticals and various biologically active compounds hence the development of newer methodologies is deemed worthy. Considering their biological importance and ongoing demand Govaerts *et al*. in 2020 demonstrated a Ru-catalyzed diamination of alkene (**11**) in the presence of blue LEDs (**Figure 10**) [14]. This methodology exploits the generation of aminium radicals from the in situ generated *N*-chloroamines and their capability to react with alkenes via anti-Markovnikov addition.

According to the depicted mechanism (**Figure 10**) initially, chlorination of an alkylamine with NCS occurs followed by the addition of a strong Brønsted acid generates a highly activated *N*-chloroammonium intermediate (A) which upon SET via photoexcited state of Ru(bpy)3 2+ creates the intermediate (B). This amminium radical intermediate (B) adds to the olefin (**11**) to give anti-Markovnikov intermediate (C). Simultaneously the β-ammonium radical intermediate (C) reacts with intermediate (A) restoring the intermediate (B) and provide the protonated βchloroamine intermediate (D) which gives intermediate (E) followed by ringopening by a second alkyl amine (e.g., Et2NH) to give the product (**12**).

Considering the importance of acyl amide, Hari *et al*. in 2014 established a photochemical method (**Figure 11**) for the synthesis of functionalized amide (**14**) using diazonium salt as the cheap and environment-friendly arylation partner and alkene (**13**). [15] The photo Meerwein arylation reaction is applied only for the formation of aryl–alkene coupling products. As suggested in the mechanism,

*Construction of C-N Bond* via *Visible-Light-Mediated Difunctionalization of Alkenes DOI: http://dx.doi.org/10.5772/intechopen.98949*

**Figure 10.**

*Synthesis of 1, 2-Diamination product.*

**Figure 11.** *Synthesis of amino-Arylation product.*

**Figure 12.**

*Synthesis of N-Chloro S-Fluoroalkyl Sulfoximines.*

initially an aryl radical is formed via a single-electron transfer (SET) from the excited state of the photocatalyst [Ru(bpy)3] 2+\* to a diazonium salt. Then the addition of aryl radical to alkene (**13**) generates another radical intermediate which undergoes oxidation to provide a carbenium species. Finally, the attack of a nitrile (R3CN) to the carbenium species followed by hydrolysis gives the amino-arylated product (**14**).

Considering the biological importance of sulfoximines containing compounds, Prieto *et al.* in 2019 demonstrated a method for the formation of *N*-chloro Sfluoroalkyl sulfoximines (**16**) from alkene (**15**) and sulfoximine through an atom transfer radical addition (ATRA) mechanism. A broad reaction scope was demonstrated, and various functionalised sulfoximines were well tolerated in the present protocol (**Figure 12**) [16]. Herein the photoexcited catalyst reacts with sulfoximine by SET reduction to give the sulfoximidoyl radical which is then followed by reaction with the alkene providing the alkyl radical. At this time, two different paths are possible, one is via the radical-chain path and another the catalytic path. In the radical-chain pathway the alkyl radical abstracts a chlorine atom from sulfoximine to give the compound (**16**) and generate a new sulfoximidoyl radical. In the catalytic pathway, the intermediate alkyl radical undergo oxidation by the

oxidized form of PC into a cationic species and restore the photocatalyst. Finally, the addition of chlorine atom to the cationic species afforded the compound (**16**).

Ouyang *et al*. in 2018 established an elegant method in which a photo-induced three-component reaction of styrenes (**17**) with alkyl *N*-hydroxyphthalimide (NHP) esters and amine leads to 1,2-alkylamine (**18**) (**Figure 13**) [17]. In this reaction, the alkyl NHP esters act as an alkylating agent to give 1,2-alkyl amine products from their respective alkenes. The plausible mechanism involves a visiblelight excitation of the photo redox catalyst thereby decomposing the alkyl NHP ester to an alkyl radical, CO2, and phthalimide anion. Then the addition of alkyl radical across the C=C bond of arylalkene (**17**) generates another alkyl radical which upon single electron transfer through oxidation of the [Ru(bpy)3] 3+ species provide the alkyl cation. Finally, the nucleophilic attack of amine to the cationic species delivers the final product (**18**).

#### **4.2 Ir-catalyzed C-N bond formations**

Miyazawa *et al*. in 2015 demonstrated a regiospecific synthesis of aminohydroxylation (**20**) from alkenes (**19**) by photo redox catalysis (**Figure 14**) [18]. Here *N*-protected 1-aminopyridinium salt is the key compound that provides an amidyl radical precursor in the presence of Ir-photocatalyst. The reaction proceeds via an Ir-catalyzed radical-mediated path in the presence of acetone and water under the irradiations of blue LEDs providing difunctionalized alkenes. The proposed mechanism is shown in (**Figure 14**). In the presence of visible light, the photocatalyst IrIII is excited to \*IrIII, which undergoes single electron transfer (SET) to an aminopyridinium to provide a stabilized radical (A) and a highly oxidizable Ir species IrIV. The generated amidyl radical from intermediate (A) reacts with alkene (**19**) in a regiospecific manner to give a radical intermediate (B). Then IrIII is oxidized to form an IrIV species and afford β-amino carbocation intermediate (C)

**Figure 13.** *Synthesis of 1, 2-alkyl amination product.*

**Figure 14.** *Synthesis of 1,2-Aminoalcohol.*

*Construction of C-N Bond* via *Visible-Light-Mediated Difunctionalization of Alkenes DOI: http://dx.doi.org/10.5772/intechopen.98949*

and regenerate the Ir photocatalyst to its ground state IrIII. Finally, the nucleophilic attack of H2O to the carbocation intermediate (C) produce the product 1,2 aminoalcohol (**20**).

Xu and Cai in 2019 reported a metal-catalyzed visible-light-mediated difunctionalization of alkene (**21**) where BrCF2CO2Et and amines are the coupling partner (**Figure 15**) [19]. The present strategy is equally successful for electron-poor, electron-rich, and internal alkenes. The Csp3 –Csp3 and Csp3 –N bonds are simultaneously formed under mild conditions. According to the proposed mechanism in (**Figure 15**) initially, in the presence of visible light, *fac*-IrIII(ppy)3 is excited to *fac*-IrIII(ppy)3\*, which then reacts with BrCF2CO2Et by the SET pathway to generate the ethyl difluoroacetate radical (A) and the oxidized photocatalyst *fac*- IrIV(ppy)3. Then, the selective addition of the ethyl difluoroacetate radical (A) to the alkene (**21**) generate a benzyl radical intermediate (B). This intermediate (B) undergo single-electron oxidation via the cooperative effects of the active Fe (III) species, to form the carbocation intermediate (C). Finally, the attack of an arylamine to the intermediate (C) is followed by base-mediated deprotonation to generate the difluoroalkylamination product (**22**).

Wu *et al*. in 2019 demonstrated a metal-catalyzed synthesis of β-arylsulfonyl (diarylphosphinoyl)-α,α-diarylethyl-amines (24) from readily available 1,1 diarylethylenes (**23**), arylazides, and arylsulfinic acids (**Figure 16**) [20]. This Ircatalyzed reaction takes place in the presence of blue LEDs and under the nitrogen atmosphere leading to difunctionalizations of alkenes. As per the proposed mechanism (**Figure 16**) by the irradiations of blue light, the catalyst [Ir(mppy)3] 3+ is excited to [Ir(mppy)3] 3+\* through energy transfer. Then, arylsulfinic acid and [Ir (mppy)3] 3+\* participate in a SET process to generate [Ir(mppy)3] 2+ and arylsulfonyl radical (A). Then the addition of alkene (**23**) to the intermediate (A) form the α αdiarylalkyl radical (B). Simultaneously, [Ir(mppy)3] 3+\* transfers its energy to the arylazide resulting in loss of N2 and the constructions of triplet nitrene intermediate **(**C). After that via a SET process and protonation, the intermediate (C) is transferred to a nitrogen radical intermediate (D) which then adds to the persistent radical intermediate (B) to give the β-arylsulfonyl(diarylphosphinoyl) α,α-diarylethyl-amines (**24**).

**Figure 15.** *Synthesis of Difluoroalkylamination product.*

**Figure 16.** *Synthesis of β-Arylsulfonyl-α, α-diarylethylamines.*

Chen *et al*. in 2019 described an Ir-catalyzed visible-light-mediated azidoarylation of alkenes in the presence of pyridines and TMSN3 (**Figure 17**) [21]. These reactions take place in the presence of *tert*-butanol and irradiations of 90 W blue LEDs. Electron-withdrawing and electron-donating group of alkene and cyanopyridine react smoothly to give the product (**26**). According to the proposed mechanism, irradiation of Ir(ppy)2(dtbbpy)PF6 produce an excited state Ir\* which would capture a single-electron from azide to generate the azido radical intermediate (A) and reducing photocatalyst IrII. Then the addition of electrophilic azido radical intermediate (A) to the alkene (**25**), produce a benzylic radical intermediate (B). A single-electron reduction between IrII and cyanopyridine generate the pyridyl radical anion intermediate (C) and regenerate the ground-state IrIII catalyst. Simultaneously, a radical–radical coupling between the transient benzylic radical intermediate (B) and the pyridyl radical anion intermediate (C) afford the intermediate (D), which can undergo elimination of a CN anion give the product (**26**).

**Figure 17.** *Synthesis of β–Azidopyridines.*

#### *Construction of C-N Bond* via *Visible-Light-Mediated Difunctionalization of Alkenes DOI: http://dx.doi.org/10.5772/intechopen.98949*

Recently, Guo *et al*. in 2021 demonstrated a photocatalytic 1,2-diamination of 1,3- dienes (**27**) in the presence of *N*-aminopyridinium and TMSNCS to affords 1,2 aminoisothiocyanation products (**28**) in high chemo- and regio-selective manner with broad substrate scope and good functional group tolerance (**Figure 18**) [22]. According to the proposed mechanism (**Figure 18**) the visible light excites the Ircatalyst which reduced *N*-aminopyridinium salt to produce a radical intermediate (A) and underwent dissociations to generate a nitrogen-cantered radical (B) and 2,4,6-collidine. Regioselective addition of intermediate (B) to 1,3-diene (**27**) afford an allylic intermediate (C). Eventually, oxidation of the intermediate (**C**) by IrIV afforded a carbocation intermediate (D) with concurrent regeneration of IrIII species. Nucleophilic addition of TMSNCS to the intermediate (D) generated a mixture of 1,2-aminoisothiocyanation (**28**) and 1,2-aminothiocyanation products.

An elegant method for the synthesis of β-sulfonyl amides (**30**) is reported by Zong *et al.* in 2019 through an acid promoted photochemical reaction of styrenes (**29**), aryldiazonium tetrafluoroborates, sulfur dioxide, nitriles, and water (**Figure 19**) [23]. This visible-light-mediated vicinal aminosulfonylation of an alkene with the insertion of SO2 giving rise to β-sulfonyl amides (**30**) with high efficiency and excellent chemoselectivity, in moderate to good yields.

As depicted in **Figure 19** the plausible mechanism involves the interaction of aryldiazonium tetrafluoroborate with DABCO(SO2)2 to generate aryl radical, sulfur dioxide, nitrogen, and DABCO radical cation. Then the aryl radical is captured by sulfur dioxide to generate an aryl sulfonyl radical intermediate (A) which subsequently attacks the alkene (**29**) to furnish a C-centered radical (B). Next with the help of photocatalyst via oxidative SET of C-central radical intermediate (B), provide a cation intermediate (C). Then the attack of nitrile to cation intermediate (C), generated another cation intermediate (D). Water acts as a nucleophile in the presence of a Lewis acid to attack the cation intermediate (D), leading to compound (E). The subsequent isomerization gives β-sulfonyl amide (**30**).

Ge *et al*. in 2020 developed a metal-catalyzed three-component reaction of alkene (**31**), using a selenium ylides-based trifluoromethylation reagent, and nucleophiles such as azide, amine, alcohol, water via a radical process to

**Figure 18.** *Synthesis of 1,2-Diamination product.*

**Figure 20.** *Synthesis of Trifluoromethylative amination product.*

trifluoromethylative amination product (**32**) under mild conditions (**Figure 20**) [24]. The trifluoromethylation reagent act as a trifluoromethyl radical source. The process takes place in the presence of a Lewis acid scandium(III) trifluoromethanesulfonate Sc(OTf)3 and a photoredox catalyst [fac-Ir(ppy)3]. As per the proposed mechanism (**Figure 20**) initially, irradiation of blue light excited the photocatalyst [fac- IrIII(ppy)3] which then transfers one electron to [Sc(OTf)3•3(1)] (obtained by mixing selenium ylide-based trifluoromethylating reagent with Sc(OTf)3 via a single electron transfer(SET) process). This radical anion [Sc(OTf)3•3(1)]•� is unstable and undergoes homolytic cleavage of Se � C(CF3) bond to generate the CF3• radical. This CF3• radical addition to the styrene (**29**) gives a trifluoromethylated benzylic radical intermediate (A), which is oxidized by [IrIV(ppy)3] to a benzylic cation intermediate (B). Finally, the nucleophilic attack at the benzylic cation gives trifluoromethylated product (**30**).

Qin *et al*. in 2017 demonstrated an Ir-catalyzed protocol for the synthesis of αamino ketones and diaminations product (**34** and **34**<sup>0</sup> ) from activated olefins (**33**) *Construction of C-N Bond* via *Visible-Light-Mediated Difunctionalization of Alkenes DOI: http://dx.doi.org/10.5772/intechopen.98949*

**Figure 21.** *Synthesis of 1,2-Diamides and α-amino ketones.*

(**Figure 21**) [25]. Here o-acyl hydroxylamines are the key reacting partner for difunctionalization. Here solvent also play a pivotal role as different solvent gave different products. A plausible mechanism for the Ir-catalyzed radical diamination and α-amino ketone of active olefins is shown in (**Figure 21**). In the presence of visible-light the exited Ir-catalyst induce the reductive cleavage of reactant (A) to generate a radical (B**)** and a carboxylate anion. The *N*-centered radical (B) adds to the styrene (**33**) to produce an alkyl radical intermediate (C) with the regeneration of photocatalyst IrIII via oxidation to give a carbocation intermediate (D). In CH3CN, (D**)** is trapped by the solvent to give a nitrilium intermediate (E) through a Ritter-type process. Then attack by the intermediate (E) followed by an acyl migration afford the diamidated product (**34**<sup>0</sup> ). When DMSO is used as the solvent, intermediate (D) can also be trapped by the solvent to provide an alkoxysulfonium intermediate (E'), which undergoes a Kornblum oxidation to afford the α-amino ketone (**34**).

Qin *et al*. in 2015 demonstrated an Ir-catalyzed visible-light-mediated synthesis of chlroamines (**36**) from activated olefins (**35**) (**Figure 22**) [26]. Here *N*chlorosulfonamides served both as nitrogen and chlorine source. This methodology provides regioselective, efficient, and atom-economic method for the preparation of vicinal halo amines. The reaction goes via the generation of a nitrogen-centered radical from *N*-chlorosulfonamide by oxidative quenching of the Ir-catalyzed which is excited in the presence of blue LEDs. This nitrogen centered radical then adds to the olefin (**35**) to produce an alkyl radical which is further oxidized to a carbocation intermediate with the regeneration of IrIII. Finally, the addition of chloride anion to the carbocation gives chloraminated product (**36**).

**Figure 22.** *Synthesis of Chlroamination derivative.*

### **4.3 Cu and Pd-catalyzed C-N bond formations**

Wu *et al*. in 2019 depicted (**Figure 23**) a visible-light-mediated Cu-catalyzed difunctionalization of alkene (**37**) to give azidation product (**38**) [27]. Here the azidobenziodoxole acts as an azidating agent in the presence of acetonitrile and [Cu(dap)2]PF6 complex as the photocatalyst. While the reactions produced three types of difunctionalized products, which correspond to reaction patterns of amidoazidation, diazidation and benzoyloxy-azidation. The electronic factor of the aryl group attached to the alkene play a vital role in determining the reaction outcome. When the aryl group is rich in electron, the reaction afforded benzoyloxy-azidation product and highly electron-deficient vinyl arenes, generated diazidation products in moderate yields. When the aryl group is electron-deficient or moderately electron-rich, give predominantly amido-azidation product. Based on the proposed mechanism the reaction is initiated via single electron transfer (SET) between IBA-N3 and [Cu(dap)2] + \*, which provided an azidyl radical and [Cu(dap)2] 2+. The azide radical then attacks the alkene to produce a radical which would couple with the CH3CN-[Cu]2+ complex followed by reductive elimination to give Ritter-type intermediate. The latter is readily captured by the *o*-iodo benzoyloxylate anion and further rearrangement formed product (**38**). In another path, the radical generated from alkene is oxidized to the corresponding carbocation by IBA-N3. Then addition with *o*-iodo benzoyloxylate anion afforded the oxy-azidation products (**38**<sup>0</sup> ). When the vinyl group is attached to a strong electron-withdrawing group intermediate generated from alkene abstracts an azidyl group from IBA-N3 to give the diazidation product (**38**″).

Similarly, Fumagalli *et al*. in 2015 demonstrated a method for the synthesis of azidation derivatives (**40** and **40**<sup>0</sup> ) from activate alkenes (**39**) (**Figure 24**) [28]. The reaction is light-switchable, in the presence of light gives methoxyazidated products and in the absence of light, diazidation product is obtained. This methodology uses sustainable and cheap copper-based photocatalyst, to enable electron transfer under mild reaction conditions, thus affecting the formation of double C-N bond in dark, and C-N/C-O formation in the presence of light.

Hossain *et al*. in 2018 developed a visible-light-photocatalytic strategy for the synthesis of azido ketones (**42**) from vinyl arenes (**41**) and TMSN3 (**Figure 25**) [29]. The reactions proceed via step-economic fashion under an aerobic condition without additional oxidants. As per the mechanism (**Figure 25**) initially in the presence of light [Cu(dap)2]Cl gets excited and form an excited state intermediate (A) via oxidation with dioxygen with the release of an equivalent of ligand (dap).

**Figure 24.** *Synthesis of Azidation derivative.*

*Construction of C-N Bond* via *Visible-Light-Mediated Difunctionalization of Alkenes DOI: http://dx.doi.org/10.5772/intechopen.98949*

#### **Figure 26.** *Synthesis of Carboaminations product.*

Then the formation of an intermediate (B) rapidly occurs upon mixing of [Cu(dap) Cl2] with TMSN3. The homolytic dissociation of intermediate (B) generates another intermediate (C) and an azide radical. After that the azide radical attacks the alkene to form a stabilized radical intermediate (D), which further reacts with oxygen to form intermediate (E). Then this radical intermediate binds to intermediate(C) to form a CuII species intermediate (F). Finally, the release of intermediate (A) gives the ketoazide product (**42**).

Xiong *et al*. in 2019 reported a Cu-catalyzed visible-light-mediated synthesis of aminoalkylated derivative (**44**) in the presence of alkene (**43**), alkyl iodides, and carbazole (**Figure 26**) [30]. According to the proposed mechanism (**Figure 26**) initially, LnCuCl undergoes ligand exchange with the nucleophile to deliver LnCu(I)Nu (A). Then it goes to the excited-state adduct intermediate (B) in the presence of LEDs. The excited-state intermediate (B) would then involve an electron transfer with the halide to generate a radical and intermediate (C). Next, the radical attack to the alkene produces an internal radical and intermediate (D). Finally, the product (**44**) undergo reductive elimination and regenerate the Cu(I) catalyst.

Cheung *et al*. in 2020 disclose a Pd-catalyzed visible-light-mediated synthesis of aminoalkylations derivative (**46**) via 1,2-carbofunctionalization of conjugated dienes (**45**) using alkyl iodides and amines as the coupling partners (**Figure 27**) [31]. This methodology is subsequently utilizing for the late-stage derivatization of complex molecules which is useful in drugs discovery. The multi-component reaction uses readily available reaction partners with broad substrate scope and does not require any exogenous photosensitizers or external oxidants.

The proposed mechanism is shown in (**Figure 27**), at first, the photoexcited LnPd<sup>0</sup> undergo single electron transfer (SET) with alkyl iodide to generate a hybrid alkyl palladium radical intermediate (A), which attack at the terminal position of diene (**45**) to give the radical intermediate (B). This intermediate exists in equilibrium with the π-allyl complex intermediate (C). A subsequent nucleophilic attack of the amine forms the carbofunctionalization product (**46**) and regenerates the palladium catalyst.

**Figure 27.** *Synthesis of Aminoalkylations derivative.*
