Substitution, design strategies

Hazard and Risk Analysis Consideration should be given to identifying process hazards as early as possible in the process equipment design, so that measures can be taken to reduce or eliminate the hazards. Inherently safer design strategies, such as minimize, substitute, moderate, and simplify, should be implemented. 

Importantly, in both 4 and 5, these types of esters were found to retain their potency as beta-blockers. Even more important for the hypothesis and new design strategy, however, the carboxylic acid versions were found to be essentially inactive - just what was needed. As mentioned for 5, a substituted phenyl-ring was re-... 

Fig. 3. Design strategy for the synthesis of prazosin-related quinazolines by inserting a substituent on the furan ring of 2 or 3 or by replacing the furan ring of 2 with an (un)substituted phenyl ring. See Table 2 for structures.

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