It's been a great week for the PZQ project, since we've had an injection of real help from the people we most need - process chemists. Much of this has arisen from a discussion I started on LinkedIn, which then became emails, but all participants have either actively participated on this site, or granted permission for the posting of information here.
Dear Matt,
This may come too late, but you could look into using conditions published by AGMBarrett for aliphatic nitro group reductions, by transfer hydrogenation. Its in Tet Lett but there's an open-access link here: http://www.erowid.org/archive/rhodium/chemistry/nitro2amine.cth.pd-af.html
regards
Nick
There may be members of this community who do not yet have direct experience of developing a new medicine from concept to pharmacy shelf. Be assured, there is a lot more to it than "just" the synthesis of the API. Why not take advantage of a Free ACS Webcast on May 6, 2010 Thurs 2:00-3:00 PM ET
From a Beaker to a Bottle: Overview of the Drug Discovery and Development Process for Small Molecule Therapeutics
I'd like to suggest that this approach deserves its own thread - at present it is mentioned within the stereoselective synthesis project. I think it is more important than that - if you agree, there is existing content that should be migrated across to here.
Analytical chromatography
There are many ways to analyse PZQ with enantioselective chromatography. The approach used in-house at Sydney. We used ChiralcelOD-H column, Solvents: Hex:IPA:TEA 60:40:0.1, Flow Rate: 0.7 mL/min. The retention times were 12.362 & 14.932 mins. Sample HPLC trace is posted below. Preparative chromatography
Paper detailing the preparative separation of PZQ enantiomers by Intervet:
PZQ can't be resolved as-is (unless anyone has any bright ideas how to resolve amides). One of the most promising strategies to prepare enantiopure praziquantel (using a strategy that starts from the racemate) is a classical resolution of praziquanamine (1, "PZQamine").
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