Concise Pathway to New Multifunctionalized Constrained Pentacin Derivatives by Means of Two Stereospecific Tandem Reactions
Starting from Boc-activated diketopiperazines, original bicyclic derivatives of trans- and cis-2-aminocyclopentanecarboxylic acid were prepared by using two stereospecific tandem reactions. One of them is a tandem transannular rearrangement of activated lactams/alkylation process leading to the stereoselective synthesis of suitably chiral pyrrolidine-2,4-diones, allowing subsequent Michael-initiated ring closure, a simple and concise route to original multifunctionalized alicyclic β-amino esters.
In this paper, the authors identify the scalability bottlenecks of an unstructured grid CFD code (PETSc-FUN3D) by studying the impact of several algorithmic and architectural parameters and by examining different programming models. The authors discuss the basic performance characteristics of this PDE code with the help of simple performance models developed in their earlier work, presenting primarily experimental results. In addition to achieving good per-processor performance (which has been addressed in the cited work and without which scalability claims are suspect) they strive to improve the implementation and convergence scalability of PETSc-FUN3D on thousands of processors.