Week 16 Mega Chemist Challenge Clues

Seen as though this weeks problem is quite easy I will keep the clues sparse.

PhD completed in 1999 under the supervision of Dr. Jonathan B. Spencer

Post-Doc with Professor Amos B Smith

Junior Research Fellow in the lab of Professor Steve Ley

Independent research career began in 2003


Mega Chemist Challenge Week 16

This one should be pretty easy, especially if you are in the UK.  Answers on a postcard or via @karldcollins or email.

Mega Chemist Challenge Solution Week 15

Last weeks Mega Chemist is Georg Wittig who shared the Nobel Prize in 1979 with Herbert C. Brown. He undertook his graduate studies and then his habilitation (completed in 1926) – alongside another future Nobel laureate, Karl Ziegler – under the supervision of  Karl von Auwers at Marburg University. Wittig spent his entire career in Germany, beginning as a lecturer at Marburg before moving to the Braunschweig Institute of Technology on the invitation of Karl Fries. Wittig then moved to the University of Freiburg in 1937 on the invitation of Hermann Staudinger (yet another Nobel laureate), before moving to the University of Tübingen (as successor to Schlenk) in 1944 as Professor and Faculty Director. Wittig ended his career as Professor and Faculty Director at the University of Heidelberg and remained there as Professor Emeritus from 1967.

Wittig is best known for the eponymous Wittig olefination (DOI: 10.1002/cber.19540870919 – in German), though the rearrangements of aryl alkyl ethers to tertiary alcohols and that of allylic ethers to homoallylic alcohols also bear his name. The Wittig olefination is one of the most widely known and widely use reactions in organic chemistry and the mechanism taught undergraduate level is known by all.  However, beyond undergraduate level the mechanism is anything but widely accepted and investigation into its finer points is extensive. [This 2009 theoretical studies has a short introduction to the mechanistic debate and all the appropriate references DOI: 10.1007/s00214-009-0521-4].

As the Wittig is taught at undergraduate level, we know that the use of a non-stabilised ylide exclusively forms Z-olefins, and in contrast a stabilised ylide will give exclusively E-olefins (explained by the reversibility of the oxaphosphetane formation), though the reality of this is never quite as good! [Undergraduates beware – the truth of organic chemistry is cleverly hidden from you until you make that decision to step into a synthesis lab: do not take that step lightly as at this point you will be shackled to the fume cupboard on an extendable dog lead that retracts at the call of your name.]

Although the ability to switch the olefin geometry by selection of a stabilised or non-stabilised ylide is useful, it is limited by the need to have an electron withdrawing group, whether you want it or not, to generate transselectivity. An alternative [I am not sure why this is not more widely known or used – maybe the selectivity is generally not great, but the examples I have seen seem pretty good] is to use a Schlosser modification of the Wittig reaction to enable the use of non-stabilised ylides to generate trans-olefins.

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Mega Chemist Challenge Clues Week 15

This weeks Mega Chemist died in 1987 at the age of 90 in West Germany. He was drafted into the German army during the first world war and spent a year as a British prisoner of war before he restarted his chemistry career at the University of Marburg.  He completed his PhD and his habilitation under the supervision of Karl von Auwers and subsequently had a highly successful career culminating in being awarded the Nobel Prize for his development of the use of phosphorus-containing compounds in organic synthesis. Two rearrangements bear his name.