Chemistry 30A3 Fall 2011 Labs Dr. Troendle 33

Chemistry 30A3 Fall 2011 Labs Dr. Troendle 33 - excess,...

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Chemical Biology 3OA3, September 2009 Page 33 E XPERIMENT 4 C ATALYSIS BY Y EAST : REDUCTION OF 1- PHENYL -1,2- PROPANEDIONE Introduction As noted in the introduction to Experiment 2, the use of biological methods to effect chemical transformations has proved useful in chemical synthesis, not least because of the spectacular control of selectivity that can be achieved. This is one example of integrating biology with chemistry, a field that has become known as chemical biology . In this experiment, you will use baker’s yeast ( Saccharomyces cerevisiae ) to reduce both carbonyl groups of 1-phenyl-1,2-propanedione ( 1 ), leading to 1-phenyl-1,2-propanediol ( 2 ) as the major product. In this process, two new stereogenic centres are produced from the achiral starting material. The major product is a single isomer, which is formed in > 98% enantiomeric
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Unformatted text preview: excess, and in high diastereomeric excess. It has the ( R ) configuration at C-1. You will establish the absolute configuration at C-2. O O OH O O OH OH OH 1 2 3 4 1 2 1 2 Start your report by drawing out the reaction scheme, showing all the possible stereoisomers of diol 2 , and labelling each chiral centre. Indicate which isomers have the R configuration at C-1. This reaction can proceed through two possible intermediates, ketols 3 and 4 . You need to bear this in mind when identifying your product How can the structure and stereochemistry of the product be confirmed? How is enantiomeric excess determined? These and other questions form an open-ended discussion that enables you to explore this aspect of chemical biology....
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This note was uploaded on 01/08/2012 for the course CHM 30A3 taught by Professor Ricktroendle during the Fall '11 term at UNF.

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