Chemist In A Transition State

October 31, 2006

Happy Birthday, Mom!

Filed under: Uncategorized — Tynchtyk @ 5:50 pm

Today is my Mother’s birthday.

It is very sad to spend the fifth consecutive year being not with her on her birthday… Last time I saw my Mother was on February 12, 2006 when I was at home in winter holidays.

Happy Birthday, Mom!!!

October 30, 2006

Sweet ASAP from JACS!

Filed under: Organic Chemistry — Tynchtyk @ 3:17 pm

I enjoyed this article so much that I could’t help blogging about it.

Prof. Yudin and his graduate student synthesized a “new class of bench-stable compounds”, namely Aziridine Aldehydes, which contain “seemingly incompatible”  functional groups: an aldehyde and an unprotected secondary amine”. These compounds exist in a dimeric form and are stable against self-condensation:

aziridines.gif

The authors’ explanation of why iminium species are not formed is that, that an aziridine ring strain imposes a high energetic barrier for that process.

Now what is most interesting with these compounds is that they can construct complex structures that resemble natural products in one step! Here you are:

 complex-structure.gif

Moreover,  conditions were found in which only the syn diastereomer is formed with high  diastereoselectivity.

The aziridine ring can be selectively opened by a thiol:

aziridine-opening.gif

Beautiful chemistry with high yields!!!

October 27, 2006

Friday Night Retrosynthesis: Welwistatin

Filed under: Chalk Talk, Organic Chemistry — Tynchtyk @ 4:07 pm

In previous post I presented structures of some most popular targets for Total Synthesis currently. One of them is Welwistatin, the molecule responsible for the MDR-reversing activity of the algal extracts. Currently, many labs are trying to synthesize this little beastie but no one has synthesized it yet.

Notable features of this alkaloid are 2 quaternary carbons and a bicyclo[4.3.1]decane carbon skeleton.

The key steps of my strategy are: 1 -  a Diels-Alder  reaction of a furan derivative and a presented dienophile

2 - Pinacole-like step which installs the core skeleton and a quaternary center.

After that few simple transformations would give the desired Target:

welwistatin2.gif

P.S. Dear practicioners of Total Synthesis, if you are going to synthesize this molecule inspired by my Retrosynthesis could you be so kind to give a reference to my blog so that my traffics increase:))

October 25, 2006

Most popular targets for Total Synthesis

Filed under: Organic Chemistry — Tynchtyk @ 6:08 pm

To select graduate schools where I would like to study I have visited numerous sites of research groups(my selection was based solely on research interests of faculty not on the school’s rank) . I have visited homepages of all organic chemists listed at www.organiclinks.net .  Most of them contain description of research interests and structures of target natural products. Based on my search I can conclude that most popular natural products are:

1 - Chartelline family of alkaloids(Recently the only synthesis of Chartelline C was reported by Baran et.al);

2 - Welwitindolinones(Welwistatin is the most popular but has not succumbed to total synthesis yet);

3 - Palauamine( too many nitrogens and an odd chlorine)

4 - Actinophyllic Acid

5 - Guanacastapenes

5 - Abyssomicin C (Two Total Syntheses appeared recently by Sorensen and Nicolaou groups)

6 - Recently, structure of a new beautiful antibiotic  Platensimycin was published. Only 4 monthes after that the Nicolaou lab published its Total Synthesis in ACIEE. 

mostpopular.GIF

October 22, 2006

In the beginning…

Filed under: Uncategorized — Tynchtyk @ 1:09 pm

Welcome everybody!

Most probably you are a chemist who  found himself or herself here while googling about transition state or smth related to it. I am sorry if you are dissappointed not finding anything you wanted to see…

Anyway, this blog is related to chemistry and I will write mostly about Organic Chemistry.

I am a senior undergrad who loves Organic Chemistry and who is preparing for graduate school(wish me luck guys). 

 So, let’s start…

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