Parallel case synthesis directive

Here is an example of a parallel case synthesis directive. 

The information that all case item values are mutually exclusive needs to be passed to the synthesis tool. This is done by using a synthesis directive called parallel case. When such a directive is attached to a case statement, a synthesis tool interprets the case statement as if all case items are mutually exclusive. Since the synthesis directive appears as a comment in the Verilog HDL model, it has no effect on the language semantics of the model. This implies that no priority logic is synthesized for the case statement control instead decoding logic is used. Here is the case statement with the parallel case directive. 

A word of caution. The synthesis directive, parallel case, can potentially cause a functional mismatch between the design model and the synthesized netlist Chapter 5 elaborates on this further. 

The two synthesis directives we have seen so far, full case and parallel case, can potentially cause functional mismatches to occur between the design model and the synthesized netlist. The problem is that these directives are recognized only by a synthesis tool and not by a simulation tool. In either of the cases, if the designer is not careful in specifying the directive, mismatches can occur. 

Recommendation Use caution when using the synthesis directives full case and parallel case. Use only if really necessary. 

As in the case of benzimidazole, a parallel synthesis of benzoxazoles was described. The authors report that mixing directly differently substituted o-amino phenols 193 with acylating agents 194 and heating at 200 °C for 10-15 min under microwave irradiation, a collection of benzoxazoles 195 was obtained (Scheme 70). With this reaction, a 48-member library of benzoxazoles with different substituents on the aromatic rings was obtained [125]. 

Figure 4.26 (a) DNA replication at low resolution (for example as seen by electron microscopy). Only one replication fork is visible and it appears that both strands of the parental DNA replicate continuously in the same direction, which cannot be the case, since the two strands of parental DNA are anti-parallel, (b) The problem is solved by the priming of DNA synthesis with short RNA primers, whose 3 -hydroxyl can be used by DNA polymerase, producing Okazaki fragments, while on the other strand, DNA synthesis is continuous. (From Voet and Voet, 2004. Reproduced with permission from John Wiley Sons., Inc.)... 

Coats reported a parallel synthesis of delta/mu agonists as depicted in Scheme 15.27. Both solid and solution-phase techniques were evaluated with regard to the reactivity of the vinyl bromide template but solution-phase couplings resulted in more rapid reactions. In the latter case it was found that the Suzuki-Miyaura reaction could be applied directly to the reaction mixture of the preceding reductive amination, thus ensuring a relatively rapid and easy synthetic route to a library of 192 compounds [66]. 

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