Q.30-21E - Organic Chemistry (Mcmurry)

Question

Heating (1Z,3Z,5Z)-1,3,5-cyclononatriene to 100°C causes cyclization and formation of a bicyclic product. Is the reaction conrotatory or disrotatory? What is the stereochemical relationship of the two hydrogens at the ring junctions, cis or trans?

Step-by-Step Solution

Answer

To check whether the formation and cyclization of the bicyclic product will take place in a conrotatory or disrotatory manner.

Reaction involving triene’s cyclization

The reaction which involves cyclization of triene. There is an involvement of electron pair odd number and the reaction will occur under the thermal condition in a disrotatory manner. This is a cis relationship between two hydrogens at the ring. 

Cyclization and formation of bicyclic product

There is a formation and cyclization of the bicyclic product when it is treated with 100^oC under thermal conditions is a disrotatory manner.