However, it is crucial to consider that the aryl acid intermediate formed in the first step has a propensity for homocoupling in the second step, particularly when the aryl rings are more electron-rich. Consequently, electron-rich aryl iodides are categorized as type III, making them more suitable for the second coupling. As a general guideline, electron-deficient (hetero)arenes are preferred in the first coupling, as they provide high yields and facilitate a more efficient second arylation. The importance of proper coupling choreography is exemplified in the following case studies. For instance, compound 66 can be retrosynthetically disconnected to simple 1-bromocyclobutane-1-carboxylic acid 14a, 1-iodo-3,5bis(trifluoromethyl)benzene 91, and 5-bromopyrimidine 24. According to the guidelines, 91 and 24 correspond to Type I and Type III arenes, respectively. Following the user guide, heteroarene 91 (Type I) is coupled first followed by 24 (Type III), delivering compound 66 with an overall yield of 32% (path I). In contrast, inverting the preferred coupling order (path II) fails as the first coupling of 24 to 14a does not proceed. Similarly, compound 76 can be retrosynthetically disconnected to a-bromoacid 14a, N-Me substituted iodo-indole 92 (type I), and 5-bromo-2trifluoromethyl-pyridine 93 (type II). Using the prescribed guidelines, path I yields the desired compound 76 with an overall yield of 15%. In contrast, whereas path II furnishes the corresponding tertiary acid from the type II aryl halide 93, the subsequent coupling is unworkable with aryl halide 92 (type I).