I have to finish my Diploma Thesis in a couple of days but unfortunately I don’t have access to some very much needed papers.  I will be very grateful if you will be  so kind to send me( atynchtyk@gmail.com ) PDF’s of these papers(I know it is weekend but maybe some of you are still workingin the lab):

1)   Metal Alkynyl Complexes: Synthesis and Materials

Nicholas J. Long, Dr. ^*, Charlotte K. Williams, Dr

2)  Coordination chemistry of metal alkynyl compounds

3)  Transition metal chemistry of 1,3-diynes, poly-ynes, and related compounds

4)  Some complexes of all-carbon ligands and related chemistry

Thank you very much!

I haven’t been doing any retrosynthetic analyses for a long time that my retrosynthesis skills are slowly deteriorating. Also, the number of visitors to this blog have dropped since I stopped Friday Night Retrosynthesis posts. So, to keep myself in good form and to keep this blog more or less interesting a quick retrosynthesis post is exactly what is needed.

After this brief introduction from a renowned group’s web-page:

Cortistatin A. In 2006, the unique natural product cortistatin A was reported as an extremely potent inhibitor of the migration and proliferation of HUVECs (Human Umbilical Vascular Endothelial Cells); IC50 = 180 pM (VEGF-stimulated HUVECs proliferation). It was also shown that cortistatin A is 3000 times more potent at inhibiting the proliferation of HUVECs versus other cancer and normal cell lines, suggesting that cortistatin A may be a highly selective angiogenesis inhibitor. Cortistatin A has an unprecedented structure, with a particularly challenging [3.2.1]oxabicyclooctene ring system.

…on with the retrosynthesis:

UPDATE: I agree with Greg that it is almost not possible to predict which c=c bond will cyclopropanate first. But what I wanted to say is that the core structure could (in principle) be built in this way. Here is the proposed mechanism of the key step:

UPDATE II:

… isomerization step:

BTW, (maybe) the problematic isopropyl group stereochemistry of Guanacastapen A could be installed in this manner, too. But that should be a topic of another retrosynthesis post…

So, here is the solution of the last mechanism problem:

The only answer came from an anonymous anon and his answer was absolutely right.

P.S. In fact people do this reaction in two steps: first they condense acetone and hydrazine an then it is heated in the presence of ZnCl2. Sorry if I confused some of you by not writing the details of this reaction.

Well, my previous problem was answered very quickly by Greg over at Carbon Tet who published the solution in a very understabdable way.

Another one for those who love solving mechanism problems:

You will have to determine the structure of the product and propose a plausible mechanism for this wonderful transformation.

Hope that this one will be answered as quickly as the previous one.

Try to figure out a plausible mechanism of the following transformation. Note that this problem was taken from the ICho 39 (International Chemistry Olympiad among Highschool Students) Preparatory Problems which will be held at Moscow State University in July. So, shame on you if you can’t solve it!

P.S. Friday Night Retrosynthesis Categoryis renamed to Chalk Talk. Since I am quite busy with my Diploma Project I don’t have much time to do retrosyntheses and post this kind of stuff lately. However,  you can expect to see new retrosynthesis posts from time to time.

Never knew about existence of such a journal. Found about it while reading an article in Angewandte Chemie.  You can read it free of charge at www.hyle.org .

“ I really enjoy reading the chemical blogsphere and can’t stay away anymore. My God, look at all these links on your sidebars! I want to join. May I?
  A little about this, a little about that, but mostly around organic chemistry as I can see, smell, taste (yes, I do that) and feel it. Naturally, I’ll try to make it interesting and, you know, discussible. I made up my mind about it quite a long time ago, but it is well-known that when you see a white piece of paper in front of you, it’s hard to go on beyond first lines. Even after such strong incentive as learning about my friend and ex-labmate (unfortunately, “ex”) Tynchtyk’s blog - Transition State - several months have passed. I also could have written some loud words like “stimulation of international communication in chemical science”. Could.. have… written?”

 I am glad to bring to your attention a new blog which promises to be very interesting…funny…and… organicky. http://liquidcarbon.livejournal.com is waiting for you…

You may find http://jungfreudlich.de  interesting and funny, too. 

Just received this letter,  tonight after a loooong work-day:

“Dear Mr. Amatov:

Your Application for Admission to the Graduate School in the Department of Chemistry for the Fall Term 2007, has been carefully considered by a committee of faculty members from the Department. I regret to inform you that it is not possible to recommend approval of your application. Admission is very competitive and the number of new students we can admit is limited by the size of our stuff and research facilities. We have acted on your application as promptly as possible, and we hope you will be successful in gaining admission elsewhere.

                                                                                                            Sincerely yours,

                                                                                                           ………………………      ”               

Hello Dear Chemists!

I am back from a loooooong break. Sorry for not blogging for more than a month.

As was noted in my last post I went home for a month and spent 3 weeks of my monthly stay in Kyrgyzstan teaching Organic Chemistry to a group of six brilliant highschool students that came to my former school from four regions of the country.

It was fun to try to cover all aspects of Organic Chemistry in 3 weeks ( beginning with alkanes, going throungh modern Organic Synthesis and ending with spectroscopic methods of structure determination), especially if your students are only beginners in Organic Chemistry.

Hearing when they call you ”Agai, agai!” (i.e. “Teacher, teacher!”) was strange but pleasant at the same time.

Here are some shots from the event(sorry for the quality of the pictures, they were taken by a telephone camera) :

 (Kaynar, “Yours truly”, Zamir, Shergazy, Kuban and Furkat(sitting) and Sabyr(not shown))

 ”Agai”

What a post without chemical structures and other chemical stuff!!! Here are some problems that I gave my students during quizes and ”exams” :

 Another one:

Although I was lazy and didn’t post during that time I kept reading the blogosphere and here is a problem inspired by a beautiful post from PsiPsi :

Happy holidays Fellow Chemists!

Like most of you I am going to winter holidays hiatus as soon as the examinations end.

I am looking forward to go home because I haven’t seen my parents, my brother, my sister and other relatives since  February 12, 2006.

During this time I am planning to organize a training camp for young chemists and train them for Chemistry Olympiads(IChO and International Mendeleev Chemistry Olympiad(IMChO)). Last year I enjoyed teaching at my former highschool and as a result, one of my students won bronze medals at IMChO in Armenia and at the IChO in Korea. This year( in collaboration with one REAL teacher) I want to gather the most promising students  from all  regions of Kyrgyzstan.

Best of luck to everyone  in the New Year!