Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: kriggy on October 10, 2017, 03:54:00 PM

Title: 2-substitued benzimidazole synthesis
Post by: kriggy on October 10, 2017, 03:54:00 PM

Hey, can anyone suggest reliable way to synthesize benzimidazoles substitued at position 2 (inbetween the nitrogens)? Any substituent would work, the milder the better.
We tried using imidate hydrochloride and it works OKish (methyl takes week to finish, phenyl doesnt work, while it was done in 2hrs with different substrate substitution), we tried CDI as well and it works good. I checked organic chemistry portal for some instpiration but most of the methods seems weird or quite exotic

Title: Re: 2-substitued benzimidazole synthesis
Post by: hypervalent_iodine on October 11, 2017, 01:03:03 AM

Have you encountered this paper? https://www.thieme-connect.de/DOI/DOI?10.1055/s-2007-965878 (also http://www.tandfonline.com/doi/full/10.1080/00397910902730838)

Has a lot of citations and doesn't seem overly difficult to me, provided you have access to the starting reagents.

Title: Re: 2-substitued benzimidazole synthesis
Post by: kriggy on October 12, 2017, 03:32:11 AM

Thanks. We tried it and I can see the product in HPLC (like 5%). I think the problem is that our diamine is N-substitued and precipitates when we add the aq. HCl. But suppose it can be played with by changing the conditions a bit