ORGN 754 |
| We have achieved 180 degrees directed aryl-aryl bond rotation in an achiral biaryl lactone using two synthetic steps: diastereoselective lactone ring opening reactions with a chiral nucleophile followed by re-lactonization. Preliminary results indicate that the efficiency of the directed bond rotation is 50% and 20% with a chiral amide and a chiral alkoxide nucleophile, respectively. These results demonstrate that this system is a prototypical chemically-driven synthetic molecular motor, which has the advantages of operational simplicity and flexibility in choice of “fuel” to drive the directed rotation. In order to make the system completely iterative, current efforts are focused on discovering reaction conditions to selectively remove the chiral auxiliary group preferentially with respect to the lactone group. Other chiral nucleophiles which generate intermediates from which the chiral auxiliary group is more easily cleaved or can be cleaved under orthogonal (e.g., redox or light) conditions are also being explored. Realization of these studies would result in 360 degrees iterative directed rotation in a biaryl molecular motor system. |
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Total Synthesis, Materials, Molecular Recognition, Process R&D, and Physical Organic Chemistry
8:00 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster
Division of Organic Chemistry |