Notes from Group Meeting 3 - Leaving Group Violations

Sorry for the delay, recently upgraded the computer and didn't have access to the wonderful world of ChemDraw. This post will be about the first meeting, and a second will come later this week on last weeks meeting.

This past Thursday fulfilled its promise of group problems. The majority of them, however, were something you would see in Sophomore Organic Chemistry. Sure, they were some upper end stuff, but Sophomoric none-the-less.  It did provide an opportunity to council younger students on the dangers of saying "never".

The two problems shown here each have an abnormal leaving group. The first scheme can be written a number of different ways, but it is generally agreed that the final step is the displacement of a hydroxide group. Normally, you would never see it, but in basic enough conditions you can work some magic.

The second reaction (presented here to work out on your own) shows a methyl as the leaving group, again, a big no-no. Yet, through the magic of Iodoform (hint-hint) reactions, it can pop right off.  Have fun!

-Woodward

Class Notes 2 - Heitler-London Theory

It's been a while, what with school getting under way. But I have a minute for a quick post, so I'll take it.

In Advanced Organic Chemistry the other day, we briefly talked on the Heitler-London theory. We were really getting into Valence Bonding theory, and the professor mentioned the theory in passing before moving on. So of course I had to look it up.

Walter Heitler was a German chemist who, among other things, advanced Valence Bond theory to a higher level of understanding. He applied Schrödinger's wave equation, recently published the year before, to the wave-functions of a hydrogen-hydrogen covalent bond.  He then called up a young Fritz London, and together they worked out the details of the theory that night. This theory really marks the beginning of "modern valence bond theory", and is still useful today. (Although, as I understand it, MO theory is used for most calculations.)

I'll talk more on London another time, since he has such a  remarkable career.  However, let me comment on the life of Heitler. He made significant contributions to chemistry during his time, was on the board or was the head of a number of universities, and faced a not insignificant amount of persecution. He was Jewish at the time Hitler came to power in Germany. Thankfully, Max Born was able to secure him a position out of country in Bristol, and was spared for the most part from the dealings of WWII. In his later life, he wrote a number of books on the philosophical reasoning of science and religion, which is not something we talk much about these days. (Perhaps another blog post on this front?)

Bottom line, let us honor our scientific ancestors and respect the work they've done. Standing on the shoulders of giants and all that.

Notes from Group Meeting - 2

School year officially started this week, meaning we finally have group meetings again. A couple of people were mentioned jokingly between professors that I had to look up, cause I sure don't want to be left out of the loop.

The first person was Phil Baran. We were discussing a synthesis, and the presenter showed how a group achieved their goal by performing six steps to protect, oxidize, deprotect, an so on. Professor B said to Professor A (paraphrase), "With that many steps just for protection, Phil Baran must be in pain!"

Google tells me Phil S. Baran is a professor at Scripps, and his focus is on "Aiming for the Ideal Synthesis". His mantra: "Total synthesis in this century must therefore be keenly aware of this ultimate challenge – to be able to provide large quantities of complex natural products with a minimum amount of labor and material expenses." He follows JB Hendrickson's dictum, …creates a complex molecule… in a sequence of only construction reactions involving no intermediary refunctionalizations, and leading directly to the target, not only its skeleton but also its correctly placed functionality." He recently published in Science about a 14 step efficient synthesis that his group performed. He is well respected in his field. Many of his papers are protecting group free, and would be considered 'elegant'. Hence, the joke from Prof B to A.

The second person, I didn't actually get his name down, or exactly what happened. We were taking about ethics with all of the apparent fraud going on, and Prof A mentions Jim/John/Joe McNair/McClair/McBear and how he faked his NMR spectra for cylcohexanol (?). This was the big deal in the 90's, or so I'm told, long before I was ever in the industry. I wish I could find more on him, but the internet gods are not with me today. If you know more or can find something interesting about this, contact me and I will put more about him in. Anyway, that's all from group meeting this week. Next week there are practice problems, so I'll see if I can dig up anything fun/interesting/juicy about them.

-Woodward

Edit - Chris Vonnegut and Joshua Sacher (@ArgyleAardvark) have found who I was talking about. James LaClair was the man who published a synthesis of Hexacylcinol, in 2006.  Check out the blurb on Wikipedia.