How did you do? I'd love to hear your proposals for next week's mechanism so drop them down below! Subscribe for more chemistry content, and hit the notification bell to stay updated! #ScienceCommunity #MechanismMonday #OrganicChemistry
That’s so kind! Thank you 🙏🏽 In truth, I’m an inorganic chemist and I’m doing this as much for me to learn more about organic chemistry as I am trying to teach others
@@rojaslab Oh wow, you're an inorganic chemist! That's awesome. It would be amazing if you could delve into organometallic chemistry reactions and their applications in organic synthesis, such a fascinating intersection of the two fields!
My bet for this reaction was the transformation of the ketone into a hemiketal with MeOH, where the new OH would condense with the carboxylic acid to form the lactone. However, this seems equally reasonable. As for the next reaction, i could be described as an cascade double intramolecular Michael addition. First, the base deprotonates the acidic alpha position to the ketone, which attacks the alpha,beta-unsaturated ester in a Michael fashion to form the 5-membered ring. The newly formed carbanion then attacks the unsaturated ketone in the second Michael addition, forming the 6-membered ring. Finally, the carbanion (alpha to the ketone) reforms the double bond, kicking the SPh anion as a good leaving group. The E configuration of the unsaturated ester is also responsible of the syn relationship between the ester group and the adjacent proton in the ring junction.
Jose, we know that intramolecular nucleophilic addition is faster than hemiketal formation by MeOH which is a weak nucleophile. So i support mecha given in the video. Also no heat mentioned in the question, so condensation is not the case here instead using acidic H(given in question) in the start is much better as ketonic oxygen is good nucleophile, which also increases rate of further rxn.
@@rojaslab Are enolates reactive towards D.A. reactions? It is not shown in the conditions but perhaps it would be better to trap the enolate with TMS-Cl, generating something similar to danishefsky's diene, and then cleave to get the product.
Hey I'm a beginner and i did a little something for next weeks mech. First we create a stable carbocation thats directly attached to the SPh by shifting the double bond towards the carbonyl group . Then , there's a acidic hydrogen on the other side(on the double bonded carbon next to the ester) which gets abstracted by the base to give a carbanion , this is is used to make the 9 membered ring . We now kick out the SPh group and bring the shifted double bond to its correct position. Lastly, a hydride shift to form the stable 6 membered ring . This seems wild (but very fun) to me , would it even start like this?
That's so awesome that you have so much chemical intuition, even at a beginner stage. Nothing you proposed is wildly ridiculous. I like a lot of what you said and the reasoning behind it. I would encourage you to consider the first step of the mechanism being deprotonation of an alpha carbon hydrogen. This is going to form an enolate species. From there, what type of reaction do you see taking place? Remember, that all the sp3 hybridized carbons can rotate freely so don't be afraid to re-draw the intermediate in a different orientation!
In the US, we don’t have those types of classifications, so I can’t say for certain. To me, it’s just normal University level organic chemistry. Maybe something you’d see your last year of Uni!
How did you do? I'd love to hear your proposals for next week's mechanism so drop them down below! Subscribe for more chemistry content, and hit the notification bell to stay updated! #ScienceCommunity #MechanismMonday #OrganicChemistry
thank you so much for these videos, my skills have improved so much! Merry Christmas!!!
Thank YOU for saying that! Merry Christmas!
Such a great explanation! I really enjoy how these mechanisms are broken down in detail. Great job!
That’s so kind! Thank you 🙏🏽 In truth, I’m an inorganic chemist and I’m doing this as much for me to learn more about organic chemistry as I am trying to teach others
@@rojaslab Oh wow, you're an inorganic chemist! That's awesome. It would be amazing if you could delve into organometallic chemistry reactions and their applications in organic synthesis, such a fascinating intersection of the two fields!
You’ve inspired me. I’m sold!
My bet for this reaction was the transformation of the ketone into a hemiketal with MeOH, where the new OH would condense with the carboxylic acid to form the lactone. However, this seems equally reasonable.
As for the next reaction, i could be described as an cascade double intramolecular Michael addition. First, the base deprotonates the acidic alpha position to the ketone, which attacks the alpha,beta-unsaturated ester in a Michael fashion to form the 5-membered ring. The newly formed carbanion then attacks the unsaturated ketone in the second Michael addition, forming the 6-membered ring. Finally, the carbanion (alpha to the ketone) reforms the double bond, kicking the SPh anion as a good leaving group. The E configuration of the unsaturated ester is also responsible of the syn relationship between the ester group and the adjacent proton in the ring junction.
Nice work! I love that you figured out the cascade. To me, that’s the coolest part and I really enjoy those types of mechanisms
Jose, we know that intramolecular nucleophilic addition is faster than hemiketal formation by MeOH which is a weak nucleophile. So i support mecha given in the video. Also no heat mentioned in the question, so condensation is not the case here instead using acidic H(given in question) in the start is much better as ketonic oxygen is good nucleophile, which also increases rate of further rxn.
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I got it wrong 😅, went for a ketal first. Good video!
I still get things wrong all the time! We’re just having fun and I appreciate you being here!
Intramolecular diels alder with the enolate of the conjugated ketone and then E1cb with the PhS as a leaving group
Now we’re talking! Crushed it!
@@rojaslab Are enolates reactive towards D.A. reactions? It is not shown in the conditions but perhaps it would be better to trap the enolate with TMS-Cl, generating something similar to danishefsky's diene, and then cleave to get the product.
@@valros8876 Love that! Definitely a practical way to run the actual experiment, I would imagine!
Hey I'm a beginner and i did a little something for next weeks mech.
First we create a stable carbocation thats directly attached to the SPh by shifting the double bond towards the carbonyl group . Then , there's a acidic hydrogen on the other side(on the double bonded carbon next to the ester) which gets abstracted by the base to give a carbanion , this is is used to make the 9 membered ring . We now kick out the SPh group and bring the shifted double bond to its correct position.
Lastly, a hydride shift to form the stable 6 membered ring . This seems wild (but very fun) to me , would it even start like this?
That's so awesome that you have so much chemical intuition, even at a beginner stage. Nothing you proposed is wildly ridiculous. I like a lot of what you said and the reasoning behind it. I would encourage you to consider the first step of the mechanism being deprotonation of an alpha carbon hydrogen. This is going to form an enolate species. From there, what type of reaction do you see taking place? Remember, that all the sp3 hybridized carbons can rotate freely so don't be afraid to re-draw the intermediate in a different orientation!
@@rojaslab Thanks ! I'll try it out !
Is this for Alevel chemistry OCR A
In the US, we don’t have those types of classifications, so I can’t say for certain. To me, it’s just normal University level organic chemistry. Maybe something you’d see your last year of Uni!