Sunday, August 22, 2010

ACS Liveblogging Sunday Morning

10:50 am Arrived a little late this morning. I know it is only Sunday morning, but the Boston convention center seems quite dead. It took me 20 minutes just to find the one coffee cart that was open. I will be looking for the Keith Fagnou memorial symposium soon. I missed Hartwig, Sanford and Yu. Jacobson is the last speaker. I'll try to catch some of his talk.

11:15 am Jacobson is talking up reaction calorimetry for kinetic analysis. Not really new but I suppose organic chemists haven't utilized this great technique.

11:26 am Some nice new insight into the Co-salen catalyzed epoxide hydrolysis being presented. It seems using a tosylate counter ion on the cobalt is very different from Cl or OAc. The rate doesn't seem to slow down but expoxide opening is very reversible due to the good leaving group ability of tosylate. This leads to racemization and poor kinetic resolution.

11:40 am Jacobson appears to be flustered today. He's stumbling over words and seems unsure of his slides. Never the less he still has great science to share. It appears that chirality on both the activated epoxide electrophile and the Co-OH nucleophile are important for kinetic resolution. Enantioselectivity is not dependent on the chiral backbone as the ligand complex forms the same stepped configuration of the arylation groups of the salen regardless of the backbone. It is only necessary that backbone allows them to have the same sense of chirality.

11:50 am Ooh. Cyclic oligomers of the salen ligand with local C2 symmetry. Very efficient HKR at only 0.001 mol% loading. Salens connected with ether linkages. Rate is much improved over the monomeric catalyst.

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