Bad day for Th’ Gaussling to be away. The hounds are snapping at my heels at work.

I managed only to see Eric Jacobsen‘s talk on catalytic urea chemistry. Jacobsen’s system is pretty much a chiral proton ligand that can carry along a nucleophilic counter anion. Configured differently, urea’s and thiourea’s with BARF groups on the nitrogen can coordinate with chloride. This can lead to the abstraction of chloride to give a carbenium ion that can then participate in a enantioselective Pictet-Spengler type reaction. 

Jacobsen’s system resembles a radically stripped down enzyme in terms of 3-point binding interactions by hydrogen bonding.  Where Jacobsen went askew is the use of calculations to justify his mechanistic model. The models did not include solvent interactions when affording only 0-2 kcal/mol (!!) differences in energy. Naturally this did not set well with certain distinguished members of the Audience.  The ΔΔG’s did not correlate with the ee’s at all either.

A certain J.D. Roberts took great exception to Jacobsen’s molecular modeling results, resulting in the spectacle of a Harvard Professor frantically qualifying his slides and words as he back pedalled for all he was worth. There was some actual contrition there on the stage. It was quite a thing to see. There but for the grace of God go I.