The name of the synthesized compound is (+)-Polyoxin J

2. Ghosj, A. and Y. Wang: Total Synthesis of (+)-Polyoxin J. Journal of Organic Chemistry 1999, 64:2789-2795.

3. This article was reviewed by Jenny Cho, Jessica Thomes and Patrick Lytle.

4. The structure of polyoxin J.

Polyoxin J is a peptidal nucleotide antibiotics of interest of as an inhibitor of chitin biosynthesis (Merino, Pedro and Thomas Tejero, 1998). It is isolated from the culture broth of Streptomyces cacoi, and prevents chitin synthesis from the human pathogen, Candida albicans which causes thrush (http://alces.med.umn.edu/candida/Review.html).

6. The retrosynthetic formula, including the Sharpless epoxidation(5,6) is as follows.

7. The retrosynthetic formula begins with Polyoxin-J, which is formed by the coupling of a protected O-carbamoyl polyoxamic acid and a thymine polyoxin C. This step follows a removal of the protected groups. The protected groups are the polyoximic acid and thymine polyoxin C. These protected groups are synthesized stereoselectively from a protected tartrate derivative and methyl glycoside which are the starting materials.

In order to synthesize the protected 5-O-carbamoyl polyoximic acid, the researchers introduced an allylic alcohol, derived from the protected dimethyl L-tartrate. The exposure of the allylic alcohol to the Sharpless asymmetric epoxidation conditions with the diethyl D-tartrate molecule yielded a 77% anti-epoxide product.

Silica gel chromatography was used to separate the enantiomers to obtain the anti product. A comparable epoxidation, one using m-CPBA at zero degrees Celsius gave only a 65:35 mixture of anti/syn diasteromers. Therefore, the Sharpless asymmetric epoxidation proves to be the preferred reaction.

A regioselective ring opening of the epoxide using Sharpless’s techniques yielded two diols that are not included in our retrosynthetic formula. The products obtained from the ring opening are azido diols. The ingredients for such a ring opening include diisopropoxytitanium diazide in benzene at 72 degrees Celsius.

The overall goal of this lab was to obtain (+)-polyoxin J as our major product, and to utilize the Sharpless epoxidation mechanism so that we can obtain the correct configuration (anti)for synthesis.

We all shared the tasks of reviewing this article equally. We all worked on looking through articles to find the natural source of our compound, and on attatching the images to our document. Separate roles included Jenny Cho finding the article, Patrick Lytle manipulating the images and Jessica Thomes analyzing the text and molecules. We typed it together and pieced the fragments together to form the final review of our article.

Jenny Cho cho@stolaf.edu

Patrick Lytle lytle@stolaf.edu

Jessica Thomes thomesj@stolaf.edu