Comments on: Kapakahines B and F

By: John

John — Tue, 07 Jul 2009 05:32:23 +0000

Interesting peptide chemistry indeed – not often published in JACS. You would be surprised at how many un-natural amino acids (protected and unprotected) can just be bought today. You can take a look at http://www.peptideresource.com/ – they have a peptide synthesis reagent supplier list. They are also a lot of vendors listing specialty coupling reagents and peptide synthesis grade sovlents. Long live peptide synthesis chemistry!

By: Finally…Total Synthesis:NOS Day 4 at C&ENtral Science

Finally…Total Synthesis:NOS Day 4 at C&ENtral Science — Fri, 12 Jun 2009 19:10:58 +0000

[...] in mind (chemoselectivity in syntheses) and he used examples from several molecules his team has tackled to drive that point home. I won’t go into all the stories he talked about (others have done a [...]

By: Kyoto

Kyoto — Sat, 16 May 2009 08:25:27 +0000

This is absolutely a nice total synthesis and the approach solves almost all problems associated with its large scale synthesis. Also, it provides a facile synthetic route for modifying the prime core of the target; which may allow determination and improvement of any biological activities possible for analogous compounds. JACS is fine for it. One question: I read here that some papers are not fit for JACS. Can someone tell me what we expect in JACS???

By: PC

PC — Wed, 13 May 2009 23:50:08 +0000

# 100

TNPB,

I just want to make it to 100… Seems you don’t like Baran’s chemistry… This is the first synthesis of Kapakahines B and F (in gram scale). It may also be the most efficient synthesis for the next 5 or 10 years. Must be a JACS paper.

By: InfMP

InfMP — Sat, 02 May 2009 21:45:03 +0000

JACS publishes overall too many articles. I like reading Angew.

By: Tok

Tok — Thu, 23 Apr 2009 12:36:28 +0000

My respect for Angew went down a few notches after the JJLC incident, and continues to go down every day I hear nothing from them. Sorry if I’m opening old wounds. That being said, I read Angew just as often as JACS.

By: Tok

Tok — Thu, 23 Apr 2009 12:30:32 +0000

Clearly Einstein. Newton stole credit for a lot of stuff from Hooke after he died.

By: Tok

Tok — Wed, 22 Apr 2009 20:23:49 +0000

An enantiospecific reaction is one in which the enantiomer of the s.m. determins the product. For example, if you start with R and the product is S, then if it is enantiospecific, S s.m. will give you R product.
An Sn2 reaction is enantiospecific, whereas an Sn1 reaction is not.

By: Totally Natural

Totally Natural — Wed, 22 Apr 2009 13:03:29 +0000

There we go again. Nobody has to fall in love with a synthesis to make it JACS worthy. Look at what else goes to JACS, especially in the nano-bio arena, not to mention “new methodology” where a group or catalyst X is replaced by Y in a well known, often name reaction, and oops JACS commun after filling a Table with whatever works well. How many of these methods actually solve some serious synthesis problem? And how many represent even a minor improvement over existing methods?

By: PB

PB — Wed, 22 Apr 2009 10:42:33 +0000

Can an ‘enantiospecific’ process even exist – if you started with enantiopure materials (such as amino acids or sugars) and performed only coupling reactions that did not involve the stereocentres then you would get a specific enantiomer of the product, but I don’t see peptide chemists calling all their syntheses enantiospecific.

If you do a stereospecific reaction (i.e. the mechanism dictates the stereochemical outcome, so feeding in one enantiomer/diastereomer gives one product, but feeding in the opposite stereochemistry gives the corresponding opposite result) then you are not guaranteed 100% selectivity, as there can be competing reaction pathways that are not specific (Check out Ian Fleming’s work on silanes – masterful!)

so my question remains – what, if anything, does enantiospecific mean?

As European Chemist rightly this is a diasteroselective synthesis – admittedly a rather impressive one with some interesting observations about equilibria and formation of the heterocycles. It’d be interesting to ask prof Baran (or the relevant student/post-doc) what he meant when he wrote it…