## 2 Carbon-Carbon Forming Reactions
### Addition of Alkynes on Double Bond Carbon-Nitrogen  
Propargylamines--which represent important intermediates for the synthesis of significant pharmaceutical polyfunctional substances--can be synthesized by the addition of alkynes on the imine bond (Schemes 5 and 6) [22; 23; 24; 25; 26]. Propargylamines had been traditionally prepared by nucleophilic addition of magnesium or lithium acetylides on imines or their derivatives [22]. The disadvantage of such synthesis consists in the necessity of use of stoichiometric amounts of acetylides under very strict reaction conditions and absolute moisture exclusion. Simplification of this reaction brought the utilization of transition metal complexes--especially Cu(I) complexes [22]. Unfortunately, the isolation of these homogeneous complexes from the reaction mixture as well as their recycling is unfeasible. Further facilitation started with the application of Cu(II) complexes immobilized on pearl-like polystyrene and with the reaction performed as a one-pot multi-component reaction [23; 24; 25; 26]. Catalyst **9** was prepared by the reaction of L-proline with chloroacetylated pearl-like polystyrene and subsequent complexation with CuI (Scheme 5) [23]. The reaction of all three components (alkyne/aldehyde/amine: 1/2/1.25; 5 mol % Cu) catalysed by **9** proceeded under laboratory conditions [Dimethyl sulfoxide (DMSO), 2 h or 12 h at room temperature] with high yields of isolated propargylamines (48-99%). Formaldehyde and aliphatic aldehydes provided higher yields (78-99%) than aromatic aldehydes (e.g., Ph-C\(\equiv\)CH/4-MeO-C\({}_{6}\)H\({}_{4}\)CH=O/piperidine: 48%). For the reaction of phenylacetylene, formaldehyde and piperidine catalysed by catalyst **9**, several solvents were tested: water (0%), methanol (25%), toluene (30%), THF (42%), McNN (87%), DMSO (99%). For the same reaction in DMSO, the recovery and reuse of catalyst **9** was tested, when only slight decrease in yields for each cycle was observed: 99%, 99%, 98%, 95%, 90%, 90% (Scheme 5) [23]. Corresponding polymer complexes with CuBr, CuCl and CuSO\({}_{4}\) were also studied; however, they were less efficient [23]. Catalyst **10** was prepared by the reaction of \(\beta\)-alanine with polystyrene containing the -CH=O group and by subsequent complexation with CuI (Scheme 5) [24]. The reaction catalysed by catalyst **10** was performed under reflux in water (6-16 h) with the following ratio of educts: alkyne/aldehyde/amine: 1/1/1.2 (2 mol % Cu), while the obtained yields of isolated propargylamines ranged between 48-99%. For the reaction of phenylacetylene, benzaldehyde and piperidine catalysed by **10** also different solvents were tested: dichloromethane (DCM) (15%), toluene (58%), McNN (62%), THF (68%), water (95%). Furthermore, the recovery and reuse of catalyst **10** was studied for the same reaction in water, where a slight decrease in yields was observed: Cycle 1: 95%; Cycle 5: 93%; Cycle 10: 88%. Besides, the authors monitored the copper content in catalyst **10**, which remained unchanged in all of the cycles (Scheme 5) [24]. **Scheme 5**. Addition of terminal alkynes to imines catalysed by catalysts **9** and **10**. Catalyst **2** (Scheme 2) was also used by the same authors [13] for the synthesis of substituted proppargylamines (Scheme 6) [25]. The reaction of all three components (alkyne/aldehyde/amine: 1.1/1/1.1; 1 mol % Cu) catalysed by catalyst **2** proceeded in toluene (6 h, 110 \({}^{\circ}\)C) with yields of isolated propargylamines in the range of 64-95% (Scheme 6). Also in this case, different solvents were tested for the reaction of phenylacetylene, benzaldehyde and piperidine catalysed by catalyst **2**: water (trace), methanol (trace), ethanol (trace), THF (22%), McN (36%), dimethylformamide (DMF) (48%), dichloroethane (DCE) (46%), DMSO (50%) and toluene (85%). The recovery and reusing of catalyst **2** was studied for the same reaction, again with only slight decrease in yields: Cycle 1: 85%; Cycle 5: 83% (Scheme 6) [25].