## 3 Results and Discussion
Another parameter investigated, aimed at assessing possible increments of process productivity, was the solvent volume. We found that halving the volume of solvents had no impact on yield and selectivity, offering the opportunity to use reactors with half the volume. However, further reductions in volume worsened the results. The final procedure (see Section 2) gave raw **3** in a 95% isolated yield. A small amount (\(\sim\)5 mol%) of dibromolactam **3b** was also present as a contaminant (see Figure S1), likely deriving from **3** through a copper-promoted radical substitution (Figure 3). Having demonstrated the facile and regioselective generation of the bromochloro-\(\gamma\)-lactam **3** from the dichloroamide **1**, the generality of the method was expanded by considering a second substrate, characterized by a marked structural variation. Trichloroacetamides are well known reactive substrates for atom transfer radical processes, owing to the ease of formation of radical intermediates through halogen extraction [31]. However, in the absence of an effective catalytic cycle, the same radical intermediates are involved in uncontrolled processes, eroding the selectivity and synthetic appeal of the method. For instance, hydrogen transfer from the solvent may also occur, resulting in de-halogenated byproducts. Moreover, if the metal complex halogen exchange is not fast enough, the high reaction rate of trichloroacetamides should favour the formation of the \"standard\" ATRC product (**5**, Figure 5) instead of the AERC one (**6**). The technique was thus put to the test with trichloro compound **4**, prompting a re-evaluation of the operating conditions. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Entry** &
\begin{tabular}{c} **Cosolvent** \\ **(mL)** \\ \end{tabular} & **Conversion of 1 (\%)** & **Yield of 2 (\%)** & **Yield of 3 (\%)** \\ \hline
1 & McN(0.20) & 98 & 7 & 76 \\
2 & DMSO(0.10) & 100 & 3 & 87 \\
3 & DMSO(0.20) & 100 & 2 & 83 \\
4 & DMSO(0.40) & 100 & 1 & 82 \\
5 & H\({}_{2}\)O (0.02) & 100 & 2 & 97 \\
6 & H\({}_{2}\)O (0.05) & 100 & 3 & 95 \\ \hline \hline \end{tabular} Common conditions: **1** (1 mmol), Na\({}_{2}\)CO\({}_{3}\) (0.05 mmol), NaBr (1.00 mmol), Cu\({}^{(9)}\) (wire, 1 mm diam. and 20 mm long), solvent (2.0 mL, composed of EtOAc:EtOH (1:1) and cosolvent), TPMA (0.01 mmol), 16 h, 37 \({}^{\circ}\)C. GC conversions and yields are reported.  
\end{table} 
Table 2: Solvent changes in the AERC of **1**. Figure 5: ATRC (ending in blue drawing) and AERC of trichloroacetamide **4**. Following the same approach used earlier, several cyclization experiments were conducted on **4**, as shown in Table 3.  
Proceeding in a similar manner, various solvent proportions were tested (entries 1-4), revealing that a EtOAc:EtOH ratio of 1:1 (entry 3) works best, likewise to what was observed for **1**. Keeping this solvent system, its total volume was varied (entries 5 and 6), and the inclusion of small amounts of water was considered as well. These investigations resulted in high selectivities towards **6**, especially when 1.5 mL of solvent mixture and 15 mL of water were employed for each mmol of substrate (entry 5). Under these conditions (see also Section 2), raw **6** was obtained in a 96% isolated yield. A minor amount (\(\sim\) 15%, based on H NMR) of trichlorolactam **5** was also present as a contaminant (see Figure S2), formed through ATRC of substrate **4** (Figure 5). The obtained bromochloro-\(\gamma\)-lactams (**3** and **6**) can be further purified by crystallization (see Section 2).