One of the most challenging reactions we carry out as synthetic chemists is bromination of a benzylic carbon- the so called Wohl-Ziegler reaction.1 It’s a seemingly simple transformation – not particularly difficult to perform- and potentially very useful. In fact it’s a little too easy. Just add NBS and a radical initiator to an aryl
Written By: Dr John Studley
When one thinks about the chemistry of alkenes, oxidative cleavage via ozonolysis will be close to the top of the list. Certainly in the top 5. Discovered by the Swiss chemist Friedrich Schönbein in 1839, this reaction remains -both academically and industrially- a highly efficient, sustainable method for introducing oxygen into both simple feedstock materials
In the spring of 1940, John Archibald Wheeler, eminent theoretical physicist, called up his then PhD student, Richard Feynman (generally regarded as the most famous modern-age physicist) and said “Feynman- perhaps there’s only one electron in the Universe” a single entity moving backwards and forwards in time. If true it would be one hard working
I can’t begin to count the number of aryl boronic acids I’ve made and/or worked with over the years. These versatile intermediates will forever be part of the synthetic organic chemist’s toolbox. You would be hard pushed to find an organic chemist that hasn’t run a Suzuki- Miyaura cross coupling reaction at some stage in
Phenols and anilines are two of the most important building blocks in industrial chemical manufacturing. Any process capable of converting one into the other is going to generate a lot of interest, and a paper by Shi and co-workers does just that.1 Direct conversion of an aniline to a phenol is a relatively straightforward transformation
Process chemists at Genentech recently published their work on development of a kilo-scale synthesis of JAK-1 inhibitor- GDC-4379 (Figure 1).1The central heterocyclic core of the molecule consists of a 4-aminopyrazole moiety (elaborated as the pyrazolopyrimidene amide- presumably the inhibitor hinge binding fragment in the kinase active site) with an additional aryl substituent at C-3 and
Oxidation of allylic alcohols to enones, although on paper a simple reaction, usually requires insidiously toxic metals or metalloids such as chromium and selenium or hazardous peroxy- reagents.1 Scale-up of these methods remains particularly challenging. A team from GSK found themselves in precisely this position when developing a synthetic route to a steroid-derived HIV maturation
The importance of methylation in the discovery and development of bio-active small molecules is well known. I presented a webinar a couple of years ago on the “The magic methyl in medicinal chemistry,” demonstrating the unique properties of this, the simplest functional group.1 I also reviewed the state of the art in synthetic approaches to
Perhaps the best-known ring-expansion reaction is the Baeyer-Villiger oxidation, first reported in 1899- not surprisingly by Adolf von Bayer and Victor Villiger. As we’re all aware, reaction of a carbonyl with a peracid generates a Criegee-type intermediate that undergoes rate-limiting concerted rearrangement to form an ester or lactone. The migration order is substituent dependant, with
The first electrophilc aromatic substitution reaction you were taught as an undergraduate was almost certainly nitration.1 Nitration and subsequent reduction of the aryl nitro group to an aniline via high temperature metal catalysed hydrogenation remains an important industrial process. The reduction has many flavours- both in terms of the substitution pattern on the aryl (and