Here's a little snippit I've found in Science.
In this scenario, a (adjective) catalyst might (verb) with a protonated substrate through the (noun) and induce enantioselectivity in (adverb) addition reactions to the (adjective) electrophile through specific (adjective) interactions with the charged (noun).
This is what I ended up with:
In this scenario, a hairy catalyst might exercise with a protonated substrate through the fish tank and induce enantioselectivity in aggresive addition reactions to the bloated electrophile through specific sneaky interactions with the charged rattle snake.
This is the original:
In this scenario, a chiral catalyst might associate with a protonated substrate through the counteranion and induce enantioselectivity in nucleophilic addition reactions to the cationic electrophile through specific secondary interactions with the charged species.
H. Xu, S. J. Zuend, M. G. Woll, Y. Tao, E. N. Jacobsen. Asymmetric Cooperative Catalysis of Strong Brønsted Acid-Promoted Reactions using Chiral Ureas. Science 2010, 327, 986–990.
Saturday, April 3, 2010
Wednesday, March 24, 2010
Chemistry Mad Libs! First Edition!
When the oxygen does the (noun) attack it forms a (adjective) bond with (noun).
The reaction was run in a (size) (noun), where it was spun and (verb), after 3 hours it was quenched with ammonium chloride.
Mine:
When the oxygen does the dolphin attack it forms a swirly bond with your mom.
The reaction was run in a huge van, where it was spun and squeezed, after 3 hours it was quenched with ammonium chloride.
Im excited about writing these more often! Check back for more!!
Laz
The reaction was run in a (size) (noun), where it was spun and (verb), after 3 hours it was quenched with ammonium chloride.
Mine:
When the oxygen does the dolphin attack it forms a swirly bond with your mom.
The reaction was run in a huge van, where it was spun and squeezed, after 3 hours it was quenched with ammonium chloride.
Im excited about writing these more often! Check back for more!!
Laz
Saturday, December 26, 2009
Where I've Been.
Sorry about the lack of posts lately! Ive been really busy with this fall semester getting mediocre grades in my "grade boosting" semester.. I guess you lose focus when you don't have any chemistry classes. Well as of right now I'm signing up for REU projects all across the nation and some even jump a small pool of water to places where people talk funny! But hopefully, then I can get back into reading papers and crankin out some posts.
Until then you can listen to my music! www.myspace.com/kiddiekhem
Hope you like it!
Wednesday, July 29, 2009
Pranks!
Pranks are fun and can be a fun way to add some spice to your lab but how can you implement them without getting caught and hurting the science.
Whether you're acting like you didnt bring the compound to the spectra lab, when your in a group or something more complicated like what ive got for you today, its always interesting to see what happens.
This prank was executed by simply setting it on a lab member's desk, I followed up by asking "how weird was the Tungsten reaction?" He answered with "yes it was somewhat hard to follow the mechanism though." (hes not an organo-metallic guy)
Well now ive got a lab partner that thinks hes a pro at terminal alkane coupling... Id say it worked out well. Voice any lab pranks youve done in the comments!!!!
Friday, July 10, 2009
Enantioselective Total Synthesis of the Potent Anti-inflammatory (+)-Myrrhanol A
Victoriano Domingo, Lucia Silva, Horacio R. Dieguez, Jesus F. Arteagas, Jose F. Quilez del Moral, and Alejandro F. Barreo
Link to the Paper
So this latest taste of Science is freshly out of Spain. The main reaction here which caught my eye was the Ti catalyzed radical cyclization, forming a few new bonds and creating 3 stereocenters. Some other good science: a nice Negishi Carbometalation, a Suzuki using 9-BBN, and a nice epoxidation followed by reduction.
Well they started early with the Ti cyclization. It has a radical mechanism where the Titanium catalyzes a heterolitic bond breakage between the oxygen in the epoxide and the more highly substituted carbon in which its attached to. They formed this epoxide using DMAP. This carbon then attacks the neighboring sp2 carbon to form a chair, generating the sterocenter. This then pushes one electron from the pi bond over to then react with the other alkene in the same chair which then eliminates giving the lone electron back to the Titanium. Quite the proposed mechanism, but I love the end product of this reaction. It reminds me of the excitement I once had from studying the Diels Alder and the two bonds and stereocenters it formed. Here's the paper they referenced on this step PDF.
The next reaction in their synthesis was their chiral epoxidation. It looks as though the Chirality was obtained via the steric bulk of the adjacent methyl and other parts of the ring structure. After this they simply used LiAlH4 to reduce the epoxide on the less substuted carbon, affording the alcohol on the tertiary carbon.
Here is a reaction I had to do some reading on to understand. The Negishi Carbometalation has a very interesting mechanism. Essentially the Zirconium acts as a total theif and steals the Aluminum's methyl along with its electrons from the bond then stabilizes it with its two chlorine. It then sits down onto the alkyne similar to how you see HCl act with the negative chlorine, or in this case methyl, going to the more substituted carbon. After this the Zirconium and the Aluminum switch bonds the methyl on the Aluminum and the bond from the alkene on the Zirconium. Finnaly they add I2 to t solution, one iodine bonding to the Aluminum and one to the alkene. This explanation is pretty rough around the edges so if you want to check out the paper yourself here it is.
One of the later reactions of this paper was the Suzuki using 9-BBN. Here the 9-BBN was used to reduce the alkyne and place a steric Boron group on the terminal carbon. This step was followed with a Pd coupling with the vinyl idoide. I like the versatility of this step and its getting me to think about different ways to incorporate Boron groups into various structures.
Lots of fun Organometalics in this one.
Victoriano Domingo, Lucia Silva, Horacio R. Dieguez, Jesus F. Arteagas, Jose F. Quilez del Moral, and Alejandro F. Barreo
Link to the Paper
So this latest taste of Science is freshly out of Spain. The main reaction here which caught my eye was the Ti catalyzed radical cyclization, forming a few new bonds and creating 3 stereocenters. Some other good science: a nice Negishi Carbometalation, a Suzuki using 9-BBN, and a nice epoxidation followed by reduction.
Well they started early with the Ti cyclization. It has a radical mechanism where the Titanium catalyzes a heterolitic bond breakage between the oxygen in the epoxide and the more highly substituted carbon in which its attached to. They formed this epoxide using DMAP. This carbon then attacks the neighboring sp2 carbon to form a chair, generating the sterocenter. This then pushes one electron from the pi bond over to then react with the other alkene in the same chair which then eliminates giving the lone electron back to the Titanium. Quite the proposed mechanism, but I love the end product of this reaction. It reminds me of the excitement I once had from studying the Diels Alder and the two bonds and stereocenters it formed. Here's the paper they referenced on this step PDF.
The next reaction in their synthesis was their chiral epoxidation. It looks as though the Chirality was obtained via the steric bulk of the adjacent methyl and other parts of the ring structure. After this they simply used LiAlH4 to reduce the epoxide on the less substuted carbon, affording the alcohol on the tertiary carbon.
Here is a reaction I had to do some reading on to understand. The Negishi Carbometalation has a very interesting mechanism. Essentially the Zirconium acts as a total theif and steals the Aluminum's methyl along with its electrons from the bond then stabilizes it with its two chlorine. It then sits down onto the alkyne similar to how you see HCl act with the negative chlorine, or in this case methyl, going to the more substituted carbon. After this the Zirconium and the Aluminum switch bonds the methyl on the Aluminum and the bond from the alkene on the Zirconium. Finnaly they add I2 to t solution, one iodine bonding to the Aluminum and one to the alkene. This explanation is pretty rough around the edges so if you want to check out the paper yourself here it is.
One of the later reactions of this paper was the Suzuki using 9-BBN. Here the 9-BBN was used to reduce the alkyne and place a steric Boron group on the terminal carbon. This step was followed with a Pd coupling with the vinyl idoide. I like the versatility of this step and its getting me to think about different ways to incorporate Boron groups into various structures.
Lots of fun Organometalics in this one.
Tuesday, July 7, 2009
Big Adventure in Little City
So now that I've gotten that Jackie Chan sounding title out of the way, ill get to the story.
So the plan was to play tunes and Skype untill the sun began to set, get on a city bus and take it round trip, to see the city. Soon i was wandering around the
medschool looking for the South bus. Things seemed to look a little different now that it was dark and I ended up spending a decent amount of time wandering outside of the medschool. I was thrilled with that though, it worked out perfect, Saw all of the buildings from a different road which look alot prettier than the normal view. Ended up in a cove within the medschool with some very pretty locked doors, and then when i broke out of it and found the stop, the hospital helicopter was taking off (it was dark now) and it was soo coool! Snagged a video on the phone. It wasn't long untill i was hopping on the 935 bus, but before that i met a guy that was shot 4 times! The initial bus ride was awesome! It had layered rows and I got on a seat near the back which sat alot higher than the rest, to get a better view. Okay well now im going to start telling the story from someone who has already finished the trip and understands what the heck happened. At the Monroe stop the bus driver got out and got into a car that was sitting there as we pulled up. She was in that parked car for 10 minutes untill a cop walked up. I have no clue what was said, but 5 minutes later the bus rejoined its course. Soon we were driving through downtown, tall buildings, lots of lights, it was gorgeous. When we got to the downtown stop some people were exchanged and then a bus driver got on. He spoke with her for around five minutes, in what seemed to be a heated conversation. Then we headed north of the city. Lots of new unseen buildings, The beer factory from a new side, and this is where most of the people on the bus requested stops. After every one else got off, she ended up pulling into a Wegmans parking lot, behind a parked bus, announcing this is the last stop, Soon I was questioning her how this was the last stop and not a round trip back to the hospital. She said "no it doesn't work like that" and eventually just gave "whatever" as an answer. Im guessing that talk with the other bus driver may have gotten her angry. Well I got off into this unknown area and looked around noticing there was a bus stop sign. None of the routes on the sign were for south. Instead of getting stressed out I decided there were worse places to get stranded and decided to make a trip into the Wegmans, a local grocery store. There I got some delicious Mango Slices, which helped cool me down and ended up carrying me to the end of the trip. After wandering around the store and doing some munchin. Headed back to the bus stop and met a new bus driver. I asked him if he knew where I was and told him how I became stranded. We chatted for a bit and he said he was headed downtown, where i could get on another bus to go to strong. I sat on the front seat and we talked for a good bit of the bus ride, he told me alot about Rochester and that his hometown was actually very close to my own. After seeing a completely new area of the town and how freakin cool the handicapped lift for a bus is, we made it downtown. I got on the 19 like the previous bus driver instructed, but this time I made sure we were headed to Strong Hospital, He said we were headed to Strong, but that itll be a while since it goes through the University. I was exuberant! The bus ended up taking me within 2 minutes of the dorm i stay in. It was awesome!
So now that I've gotten that Jackie Chan sounding title out of the way, ill get to the story.
So the plan was to play tunes and Skype untill the sun began to set, get on a city bus and take it round trip, to see the city. Soon i was wandering around the
medschool looking for the South bus. Things seemed to look a little different now that it was dark and I ended up spending a decent amount of time wandering outside of the medschool. I was thrilled with that though, it worked out perfect, Saw all of the buildings from a different road which look alot prettier than the normal view. Ended up in a cove within the medschool with some very pretty locked doors, and then when i broke out of it and found the stop, the hospital helicopter was taking off (it was dark now) and it was soo coool! Snagged a video on the phone. It wasn't long untill i was hopping on the 935 bus, but before that i met a guy that was shot 4 times! The initial bus ride was awesome! It had layered rows and I got on a seat near the back which sat alot higher than the rest, to get a better view. Okay well now im going to start telling the story from someone who has already finished the trip and understands what the heck happened. At the Monroe stop the bus driver got out and got into a car that was sitting there as we pulled up. She was in that parked car for 10 minutes untill a cop walked up. I have no clue what was said, but 5 minutes later the bus rejoined its course. Soon we were driving through downtown, tall buildings, lots of lights, it was gorgeous. When we got to the downtown stop some people were exchanged and then a bus driver got on. He spoke with her for around five minutes, in what seemed to be a heated conversation. Then we headed north of the city. Lots of new unseen buildings, The beer factory from a new side, and this is where most of the people on the bus requested stops. After every one else got off, she ended up pulling into a Wegmans parking lot, behind a parked bus, announcing this is the last stop, Soon I was questioning her how this was the last stop and not a round trip back to the hospital. She said "no it doesn't work like that" and eventually just gave "whatever" as an answer. Im guessing that talk with the other bus driver may have gotten her angry. Well I got off into this unknown area and looked around noticing there was a bus stop sign. None of the routes on the sign were for south. Instead of getting stressed out I decided there were worse places to get stranded and decided to make a trip into the Wegmans, a local grocery store. There I got some delicious Mango Slices, which helped cool me down and ended up carrying me to the end of the trip. After wandering around the store and doing some munchin. Headed back to the bus stop and met a new bus driver. I asked him if he knew where I was and told him how I became stranded. We chatted for a bit and he said he was headed downtown, where i could get on another bus to go to strong. I sat on the front seat and we talked for a good bit of the bus ride, he told me alot about Rochester and that his hometown was actually very close to my own. After seeing a completely new area of the town and how freakin cool the handicapped lift for a bus is, we made it downtown. I got on the 19 like the previous bus driver instructed, but this time I made sure we were headed to Strong Hospital, He said we were headed to Strong, but that itll be a while since it goes through the University. I was exuberant! The bus ended up taking me within 2 minutes of the dorm i stay in. It was awesome!
Saturday, July 4, 2009
A Versatile Route to the Tulearin Class of Macro Lactones: Synthesis of a Stereoisomer of Tulerarin A
Alexander L. Mandel, Veronique Bellosta, Dennis P. Curran and Janine Cossy.
Link to the PDF
Here is a fun little paper out of Paris. This paper really makes up for the lack of reactions you saw in the last paper, totaling about 18 (some being deprotections and protections hence the about).
The science begins with a Julia Kocienski Olefination. Here they used a Sulfone with a phenyltetrazolyl group on it to bring forth the trans alkene. The mechanism involves potassium bonding to the non conjugated carbon adjacent to the sulfone and an attack on the aldehyde. Then after a series of elimations it gives off sulfur dioxide and the phenyltetrazolyl.
After the Sharpless they used DIBAL-H to reduce the ester within the lactone into an aldehyde and then they used a methyl phosphine to afford the terminal alkene, which becomes very important later in the synthesis.
Here they used a benzylthiazolidine thione group, known as the Crimmins Chiral Auxiliary, with specific conditions in this aldol addition to attain specific stereochemistry. After that they do a simple protection and then remove the benzylthiazolidine thione group using hydroxide and peroxide.
Finally, completing the scaffolding, they carry out a ring closing metathasis using Grubbs first generation. They also attempted the reaction using other catalysts, but gave side products or did not react at all.
Some nice science, liked the Julia and seeing the Crimmins in action was nice.
Alexander L. Mandel, Veronique Bellosta, Dennis P. Curran and Janine Cossy.
Link to the PDF
Here is a fun little paper out of Paris. This paper really makes up for the lack of reactions you saw in the last paper, totaling about 18 (some being deprotections and protections hence the about).
The science begins with a Julia Kocienski Olefination. Here they used a Sulfone with a phenyltetrazolyl group on it to bring forth the trans alkene. The mechanism involves potassium bonding to the non conjugated carbon adjacent to the sulfone and an attack on the aldehyde. Then after a series of elimations it gives off sulfur dioxide and the phenyltetrazolyl.
After the Sharpless they used DIBAL-H to reduce the ester within the lactone into an aldehyde and then they used a methyl phosphine to afford the terminal alkene, which becomes very important later in the synthesis.
Here they used a benzylthiazolidine thione group, known as the Crimmins Chiral Auxiliary, with specific conditions in this aldol addition to attain specific stereochemistry. After that they do a simple protection and then remove the benzylthiazolidine thione group using hydroxide and peroxide.
Finally, completing the scaffolding, they carry out a ring closing metathasis using Grubbs first generation. They also attempted the reaction using other catalysts, but gave side products or did not react at all.
Some nice science, liked the Julia and seeing the Crimmins in action was nice.
Subscribe to:
Posts (Atom)