Rewriting the Organic Chemistry Textbooks

 


Organic chemistry scientists have discovered a big problem and it's almost 100 years old. 

Carbon molecules are characteristics by having very specific shapes and arrangements of atoms. The double bonds between molecules are called alkenes or olefins. The atoms and all those attached to them are usually in the same plane. Molecules that are not on the same plane are uncommon. The rule that scientists claim doesn't fit anymore is called Bredt's rule. It was originally reported in 1924. 

The overall description is understood as molecules cannot have a carbon-carbon bond at the ring junction of a bridged bicyclic molecule. This is referred to as a "bridgehead" position. The double bond of these structures would have distorted shapes that are different from the rigid shapes of alkenes. 

Bredt's rule has limited the usefulness of this kind of synthetic molecule in pharmaceutical research. However, a paper in the journal Science by UCLA  scientists is changing that idea.  The paper explains how to make several kinds of molecules that violate Bredt's rule, called anti-bredt olefins or ABOs. 

Neil Garg is corresponding author and the Kenneth N. Trueblood Distinguished Professor of Chemistry and Biochemistry at UCLA. He explains, "People aren't exploring anti-Bredt olefins because they think they can't. We shouldn't have rules like this or if we have them they should only exist with the constant reminder that they are guidelines not rules. It destroys creativity when we have rules that supposedly can't be overcome."

Garg's lab used molecules called silyi (pseudo) halides. They applied a fluoride source to induce an elimination reaction. This forms ABOs. ABOs are very unstable, so scientists combined another chemical that trapped the unstable molecules and made products that can be isolated. The reaction that resulted showed that ABOs can be created and trapped to give the structures some practical value.

 Garg summarizes, "There's a big push in the pharmaceutical industry to develop chemical reactions that give three dimensional structures like ours because they can be used to discover new medicines. What this study shows is that contrary to one hundred years of convention, chemists can make and use anti-Bredt olefins to make value-added products."

Comments

Post a Comment

Popular posts from this blog

Mike Giradi from Stereotimes commentary on Holostage Room Treatments

I have been  friends with Mike Giradi for a few years and he has helped me test numerous designs .    I was so honored a few weeks ago when he agreed to give these Holostages a few words.  From. Mike G. The sound was a little closed in at first, but then it really opened up to prove it is another great audio product. The noise floor is greatly reduced. I am hearing details I've never heard before. When it's in the recording, the soundstage widens in all directions. The timbre of each instrument is spot on. The six Holostages installed in my room aided in the C13 alignment of air molecules to a far greater extent than the Bybee IQSE devices I had previously been using. Every instrument had greater depth, pop and presence. Listening to classical music on movie soundtracks is incredible now. The Holostages installed on my BACCH4MAC and monoblocks was the answer to what was needed. The noise floor dropped significantly in both cases resulting in greater clarity and music...
Read more

Queen Bee 🐝

Image
  Bees hide an interesting secret. When the hive loses its queen, who alone is able to give life to the colony and maintain order in a perfectly organized society, all seems lost. The life of the hive slows down. Without new eggs, the future is lost. In a few weeks, the colony may be doomed. But the bees do not panic. Nor do they expect salvation from outside. Demonstrating extraordinary collective intelligence and profound instincts, they trigger spectacular emergency procedures, almost unimaginable in a world dominated by insects. --- ◆ The transformation begins with a simple but essential choice The worker bees choose common larvae - those who would normally be mere workers. They are nothing special. They are not born different. But their fate changes completely. They are chosen to receive a special food: royal jelly. A rare substance, produced by healthy bees, rich in proteins, vitamins and bioactive compounds. This is royal food in the purest sense of the word. The larvae fed ...
Read more

Novel Acoustic Wave Discovered

Image
  A new diffraction phenomenon was researched and published on January 14, 2025. The team was led by Tohoku University with collaboration from the Japan atomic energy agency and the RIKEN Center for emergent matter science. Surface acoustic waves (SAWs) are elastic vibrations. They travel along the surface of materials, not unlike ripples on a pond. SAWs are an important part of frequency filters used in every day devices like our cell phones. These devices change electrical signals in vibrations, or ripples. This occurs because of the piezoelectric  effect and it enables efficient signal processing. During this experiment, the team created a periodic array of magnetic nanoscale materials. The magnetic array is a sort of specialized grating that the waves passed through. The scientists were surprised. Instead of the usual symmetric defraction, the team saw something different. They observed a completely new, asymmetrical diffraction of SAWs called ‘non-reciprocal defraction’....
Read more