A short commentary on two other recent reviews.
The first is a mini-review from Kumar and Waldmann entitled “Synthesis of Natural Product Inspired Compound Collections” in Angewandte Chemie. If it sounds familiar, it should, because it’s essentially the same subject that is covered in a Chemical Reviews ASAP article that we highlighted a couple of weeks ago. As a mini-review, this one is not as exhaustive as the Chem. Review article, but the format is very similar. The quasi-racemic fluorous mixture synthesis of cytostatin by Prof. Dennis Curran is prominently featured.
It’s interesting that the editors of both journals decided to publish reviews on this topic, particularly since most of the work is solid phase supported chemistry, which has fallen out of vogue in recent years. If natural product-based libraries, however, become more popular within chemical biology and drug discovery than fluorous tags could certainly play an increased role in the generation of these libraries.
The second review is also connected to a recent F-Blog post. This one is in Tetrahedron Asymmetry and was written by Geary and Hultin covering asymmetric induction in aldol reactions. The manuscript has three major portions, chiral auxiliaries, chiral metal catalysts, and chiral organocatalysts. Within the first group a fluorous version of Evans oxazolidinone was mentioned. This fluorous chiral auxiliary provided yields and de’s similar to that found with the non-fluorous oxazolidinone, but provided the usual benefit of easy product isolation by FSPE.
One of the more interesting parts of the review was the recognition by the authors that there is a difference between fluorinated and fluorous. That is not always the case within the literature. The authors cited the use of another fluorinated oxazolidinone shown below, which is not fluorous. That auxiliary with only two fluorines is not considered fluorous since it cannot be easily removed using a standard fluorous separation technique such as fluorous solid phase extraction (FSPE). Kudos to Geary and Hultin for noting the difference.