MUSSUM - 26-4-2019 at 20:50
Hello my friends.
I would like to know if after the concerted [2 + 2] cycloaddition of a phosphate ilideo with a carbonyl group forming an oxafosfoetane. Could the
collapse of oxafosfoetane be explained by the theory of Bayer's ring tension, even though tetracycline is not completely carbonic? For the angle
between the atoms in the molecule is less than 109 ° 28 ', that is to say, such rings become very unstable, or it would be better to say that it
would have a steric factor since both O atoms and P of great volume, force the collapse in function of coulombic repulsions?
Which way of thinking would be more appropriate? By Bayer's theory or the view of electrostatic repulsions? Or even for both?
Thank you very much in advance.
/...even though tetracycline is not completely carbonic?/ wrong
/...even though cyclo is not completely carbonic?.../rigth 
Att,
Mussum
My english is very bad, sorry for this!
[Edited on 27-4-2019 by MUSSUM]
[Edited on 27-4-2019 by MUSSUM]
[Edited on 28-4-2019 by MUSSUM]
[Edited on 28-4-2019 by MUSSUM]
Sigmatropic - 26-4-2019 at 23:15
I would explain it by the oxophilicity of phosphorus.
I usually assume the oxophosphetane can collapse both ways. One way to regenerate the starting materials and the other way to the product. But since
the phosphine oxide is much more stable then the phosphorous ylid the reaction goes to completion.
For tetracycline you mean cyclobutane, tetracyclines are a class of antibiotics.
For general understanding it would be helpful to mention in the tread title that you have a question about the wittig reaction or the
Horner-Wadsworth-Emmons reaction.
[Edited on 27-4-2019 by Sigmatropic]
Sigmatrópico
MUSSUM - 27-4-2019 at 17:34
Yes, cyclobuthane. In my language "tetraciclo" is a cycle of four atoms , it is form taht we speak in Brazil, for example cyclohexane is a hexaciclo,
cylodecane is a decaciclo. it is an informal form way of referring to a cyclo compounds, but is not compatible with the IUPAC name, it is a informal
form, somewhat regional. Saying tetracycline was a mistake, sorry for this.
Thanks for your answer.
I did not know this reaction that presented me, I only knew the reaction of Wittig that is the reaction in question. Friend, could you tell me some
book only with mechanism exercises to solve?