Table of Contents
Are endo and exo products enantiomers or diastereomers?
Exo And Endo Diels-Alder Products Are Diastereomers Of Each Other. These two molecules can be separated due to the fact that they have different physical properties.
What is endo and exo products in Diels Alder reaction?
When two cyclic structures combine in a Diels Alder reaction, a third ring is formed in between the original ones. There are different ways the two original rings can combine, leading to different stereochemical outcomes. These two outcomes are called “exo” and “endo” addition.
What is endo and exo conformation?
The prefix endo is reserved for the isomer with the substituent located closest, or “syn”, to the longest bridge. The prefix exo is reserved for the isomer with the substituent located farthest, or “anti”, to the longest bridge. Here “longest” and “shortest” refer to the number of atoms that comprise the bridge.
What do the terms endo and exo tell you about the shape of the product?
With regards to the Diels Alder products of cyclopentadiene and maleic anhydride, the term “endo” means that the orientation of the oxygens with respect to the bridge stick down. The term “exo” means that the oxygens with respect to the bridge stick up. This means that the shape of the product is not planar.
Why is Endo preferred over Exo?
1. Endo Products Tend To Be Favored In The Diels-Alder Even Though They Are More Sterically Hindered. Note that in the endo product above, the anhydride is on the underside of the new six-membered ring, whereas in the exo, it points away. This is indeed less sterically hindered.
Why is Endo preferred over exo Diels-Alder?
Endo Products Tend To Be Favored In The Diels-Alder Even Though They Are More Sterically Hindered. Note that in the endo product above, the anhydride is on the underside of the new six-membered ring, whereas in the exo, it points away. This is indeed less sterically hindered.
Why is Endo a major product?
The endo product is kinetically favored, which means that under conditions of low temperature and limited time, it will be the major product that is formed. This is because the transition state of the formation of the endo product is lower in energy due to overlap of secondary orbitals.
How to see the stereochemical relationship between endo and Exo?
Draw the other stereoisomers of the product formed from the reaction between furan and maleic anhydride. If we look at the molecule in this way, with the hydrogens highlighted on the ends of the diene and the dienophile, it may be easier to see the stereochemical relationships in the exo and endo products.
Why are there no exo products in the diene?
If all of the “outside” groups on the diene are the same as the “inside” groups, then there can’t be exo or endo. Butadiene itself, for example; the “inside” and “outside” groups are both hydrogens. If the dienophile lacks a substituent that can be distinguished as the “electron withdrawing group”, then there won’t be exo or endo.
Which is less stable endo or exo adduct?
This is because although the hydrogens of the maleic anhydride must be cis in the product, there are two possible arrangements where this is true. The actual product formed is the ‘endo’ adduct. This diastereoisomer is the less stable one, but is formed because it is the kinetic product.
How are the hydrogens on the diene related to the endo?
If we look at the molecule in this way, with the hydrogens highlighted on the ends of the diene and the dienophile, it may be easier to see the stereochemical relationships in the exo and endo products. In the exo product, the pair of hydrogens on the diene ends up cisto the pair of hydrogens on the dienophile when the rings become fused.