Question

what are the sterochemical requirements for a Diels-Alder reaction? Be specific and probide examples.

Answer 1

Queof The stezcoch omistry about the double in the o dienophila Ps Prese everd Rule it R T04 h Toh 11 04 Brom cis Но A cs derangement along the double - bond WL DE be the A- desw in ads detangement po Diels-Aldee Product ton saluron 4 0 result in a teans arrangement in the Diels alder product Rule :-2 (substituted Dienes) The two 'outside" group CA) on the cliene and up on one face of the new sixer membered eling, and the two inside groups CB l both end up on the 1 opposite face B Samer Sider samo NB outside group - side sic e Inside both on same face of new sing I g. Rule & The outside Inside Ruly fore dienes s two outside qeous I end up on the same The face CH3 f CH3 two inside group end up on the same face LEF)24-hexa diene. _ 1

Example ( Egz ) - 2 g 4, he radiane H too outside quoupe 1 Hall - I end up on the game face CHg ty CHg two inside groups and up on the same face H & CH3 Drawing each diene in the s-ei's conformation which is nerosoory for the Diels-Alder to proceed we ceo that the two coutside" groups end up on the some fole of the size membered rina of the two " inside groups also end up on the time fore of the six membered ring . another oyompleks CH2 +H - T he note that both voutsiden groups (H) end up on the same side of the ring Rule noly. When -Both the diene and Dienophile aze Substituted. Both Eule 1 & 2 both apply ____ o honon CH3 o Ln noi In coctain casses (such as fumaric acid & CE, E) 2, 4 hexadiene only one product is formed steecochemistry of the double bond is preserved in the product both outside" groups are on the same face of the new six-membered sing

Rules - When substituted dienes deact with jllbctitwed_Dienophiles g Diasteceumere may also formed. C Exo f Endo). When we combine a substitude diene such as CEE) 2. 4 hexadiene with maleic ca ci d & follow both Ruleht of lulet there are actually two possible preoclucts 대로 Exo & Endo let examine the Diels alder maction q CE, E24 hexadiene Following Rule 1 & Rule 2 - The stereochemistry about the dienophile substituent - are in cis in the proødet - The two outsicle group on the diene end upon - the some face 543 out side group n (CH₂) of diene -413 ? Bo is cis Endo diastero. to electron majo withdrawing group of dien op wile T itleon otficte gratif the Bon -- EH37. of diene is trant Exoceste comes to electro minor a withdrawin group of dienoplits on ht ch MyH3 L o ttiett gratif