## 2 Sequences Based upon Alkynylation and Carbopalladative Insertions
Encouraged by the success of this three-component process, the strategy was further elaborated involving in situ generation of azides in a four-component one-pot sequence. Removal of the Boc group was carried out as a separate step under relatively mild conditions and some derivatives obtained by this concise strategy exhibited satisfactory kinase inhibition activity. **Scheme 8. ** Consecutive three-component synthesis of _N_-Boc 3-triazoleyl (aza)indoles and azoles **15** via Sonogashira alkynylation-desilylation-CuAAC sequence. Likewise, aroyl chlorides successfully underwent Sonogashira coupling and desilylation steps to give terminally unsubstituted yones that were subsequently transformed to 1-substituted-4-phenylacyl-1_H_-1,2,3-triazoles **16** under dielectric heating (Scheme 9) [70]. **Scheme 9. ** Consecutive three-component synthesis of 1-substituted 4-acyl-1_H_-1,2,3-triazoles **16** via Sonogashira alkynylation-desilylation-CuAAC sequence. In a related study, the one-pot synthesis of 1-substituted 4-acyl-triazole **17** was improved by (1) switching to the more robust TIPS (tris(isopropyl)silyl) protecting group; (2) reducing the amount of triethylamine in the Sonogashira step to one stoichiometrically necessary equivalent, as previously shown for TMS-alkynone formation by [PERSON] and [PERSON] [79]; and (3) employing AgF as an efficient reagent for the removal of the TIPS group [80]. In addition, the reaction proceeds smoothly at room temperature and gives rise to good yields (Scheme 10) [81]. **Scheme 10. ** Consecutive three-component synthesis of 1-substituted 4-acyl-1\(H\)-1,2,3-triazole **17** via Sonogashira alkynylation-desilylation-CuAAC sequence. Not many methods for the synthesis of \(N\)-unsubstituted triazoles are available [82] and their potential biological activity encouraged the development of synthetic strategies. This led to the development of a three-component one-pot synthesis of 4,5-disubstituted-1,2,3-2\(H\)-triazole **18** starting from acid chlorides, terminal acetylenes, and sodium azide via ultrasonication promoted Sonogashira coupling-1,3-dipolar cycloaddition (Scheme 11) [83]. **Scheme 11. ** Consecutive three-component synthesis of 4,5-disubstituted-1,2,3-2\(H\)-triazole **18** via Sonogashira alkynylation-cycloaddition sequence. The developed strategy exhibited a wide range of tolerated substrates, also showing its compatibility with both electron donating and electron withdrawing substituents. Thus such 1,2,3-2\(H\)-triazoleprovided an opportunity for further exploration of their inclination towards reacting in coupling reactions. The screening of various substrates showed the regioselective _N_-2 _arylation furnishing 1,4,5-trisubstituted-1,2,3-triazoles by nucleophilic aromatic substitution with 1-chloro-4-nitrobenzene._  
_Another illustration for Pd-Cu-sequentially catalyzed processes was presented by [PERSON], [PERSON], and [PERSON] with a consecutive Sonogashira-Glaser reaction, where first a (hetero)aryliodide was coupled with (trimethylsilyl)acetylene which was subsequently desilylated by potassium fluoride. Under aerobic conditions the oxidation states of Pd and Cu are altered and an alkyne dimerization furnishes the symmetrically substituted butadiynes_ **20** _in the sense of a pseudo four-component process_ _[_84_]__. This sequence was employed as an entry to a pseudo five-component synthesis of symmetrically substituted 2,5-di(hetero)arylthiiophenes_ **19** _(Scheme 12)_ _[_85_]__. Likewise, the [PERSON] group disclosed a rapid access to intensively blue luminescent 2,5-di(hetero)arylfurans when potassium hydroxide was used as the bifunctional nucleophile_ _[_86_]__. The same concept was applied to the synthesis of 3-(hetero)arylmethyl-2,5-di(hetero)aryl-substituted thiophenes in the sense of a pseudo five-component process by employing (hetero)aryl methylthiols as masked dinucleotide substrates_ _[_87_]__._  
**Scheme 12.