Totally Microwave

Got my mind on rearrangements lately. Thought this recent article (ChemInform 2013) served both to help remind us of appropriately positioned functionality can provide the right recipe…..and chiral to boot (I’m telling you that we have only scratched the surface of enantioselective microwave work — just who is going to do it.

First thing — Smiles rearrangment:

Screen Shot 2014-09-23 at 4.39.47 PM Smiles Rearrangements

Screen Shot 2014-09-23 at 4.39.57 PM Mechanistic: The arrows at work

The group was interesting in testing substituted benzoxazinones and benzothiazinones and needed an efficient method for obtaining a chiral substituent alpha to the carbonyl, but also something easily accessible from cheap starting materials. By starting with (S)-2-chloroproprionic acid, it was easy to form the desired N-Benzyl-(S)-2-chloroproprianamide by direct coupling from DCC activation. Following this, any appropriately substituted phenol or thiophenol could be added to the starting material to provide the desired final compounds following — chloro displacement and rearrangement from internal attack of the impending N…

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