The Aubé group, recently of UNC, wondered whether expensive setups from scientific vendors were potential roadblocks to wide adoption of electrochemistry. Their ideal recipe called for a direct current (DC) source capable of removing two electrons and an H from a lactam to generate an N-acyliminium ion. Looking around, the researchers realized that today's ubiquitous cellphone chargers might just do the trick. Shave back some wires, attach some copper clamps, and presto! Cheap, effective electrochemistry.**
Using their DIY e-chem setup, the Aubé group traps a wide variety of stereochemically-rich acyliminiums as the corresponding methanol adducts (19-93% yields). Now the real fun starts: there's a whole bunch of interesting arylations and other additions to these species one can access using off-the-shelf Lewis acids like titanium tetrachloride or boron trifluoride:
Adapted from Aube, Angewandte Chemie, 2015 ASAP |
I'll be excited to see small libraries of diversified products emerge from this work. However, a "one-pot" functionalization - electrochemistry with the desired nucleophile already present - still seems a distant dream.
Hopefully, the apparent ease of operation of "cellphone charger e-chem" prompts other groups to give it a try. If your group dips their toes into this field, please drop me a line in the comments section.
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*Thanks to Professor Brandon Findlay (@Chemtips) for pointing out this paper!
**I'm tickled pink at how many organic synthesis papers these days include photographic records of reaction setups. I'd like to believe that Blog Syn played a small role in advancing this change.
I am currently (pun intended) working on a setup that can build Ag/AgCl electrodes without taking up one of our potentiostats. All I need is a 1.5V DC source that can source about 1A of current, so I am going to use a simple DC-DC step-down converter from one of these ubiquitous chargers, with the intention of building a SMPS dedicated setup at some point in the future.
ReplyDeleteUse a single AA cell. As soon as your silver electrode is connected, the electrical resistance will increase dramatically. A simple wire electrode will stabilize within seconds at under a milliamp, so a single AA cell will make several dozen electrodes.
DeleteIf you really want to build a 1.5V supply, do your research carefully. Many regulator circuits do not function well at such a low voltage.
Phil Baran has demonstrated the use of a camping battery for electrodes in oxidations, in his seminar this morning at ACS Boston.
ReplyDeleteYou could even say I was live-tweeting him as he went ; )
DeleteOh yeah? Sorry I missed that. And I was surprised there hasn't been more banter about the conference on your blog, guess I missed it over on Twitter. I haven't taken the plunge and signed up for an account yet.
ReplyDeleteI like the botton view.
ReplyDeleteYour post is great, always let us learn some practical knowledge.
ReplyDelete