Chem 125 Lecture 34 12/3/08 This material is for the exclusive use of Chem 125 students at Yale and may not be copied or distributed further. It is not readily understood without reference to notes or the wiki from the lecture.

RO ~ racemic OR O OEt O O CO 2 Et Ti RO O 3) Chiral Catalysis by Titanium/Diethyltartrate Ti (etc) ROO RO + Ti O O O Ti (etc) OEt O CO 2 Et O RO Ti O O O Ti (etc) OEt O CO 2 Et 94% e.e. (3% R) with added iPr 2 NEt (discovered in 2000) n ** R S R' O Ti O O O Ti (etc) OEt O CO 2 Et + (for no obvious reason) catalytic cycle RO ROO S R R' Chiral “Oxidizing Agent” R S R' + O R S O R S Nobel Prize 2001

THE HUMAN UMBILICAL CORD

Michaelson and Oshima

Tsutomu Katsuki’s famous “recipe” Stanford Chemistry Department (1980)

Tsutomu Katsuki’s discovery -- a memorable day in 1980 at Stanford University!

"A man in California just won a Nobel Prize for mixing paint and wine!" Los Angeles Times, October, 2001

Stretch Bend Stretch-Bend Torsion Non-1,4-VDW 1,4-VDW TOTAL Cyclobutane Puckering (by Molecular Mechanics) Torsion vs. Bend Relaxed Planar

Stretch Bend Stretch-Bend Torsion Non-1,4-VDW 1,4-VDW TOTAL Cyclopentane Puckering (by Molecular Mechanics) "Envelope" Relaxed Planar

e.g. What is the source of the barrier to c-hexane ring flip? two butane gauche  eclipsed (~7 kcal/mole) But why does the plastic model click? Baeyer Angle Strain +7° +5° -3° +5° Like a plastic model, molecular mechanics is satisfying because not only does it say what a structure should be, it can also say “why”.

Are They “True”? YES Are Molecular Mechanics Programs Useful? NO

End of Lecture 34 Dec. 3, 2008