Question

Hi I am struggling with this set of qeuestions on diels alder chemistry! Thanks so much!

2, 3-Diphenytcyciopropenone (see structure below) form* an addition product with HBr that exhibits the properties of an ionic substance (i n a salt) Modify She starting material drawn and suggest a structure for this product and a reason for its existence as a stable entity. The benzene is a good and will abominate under electrophone aromatic substitution. The product is a stable aromatic cyclopropane The conjugated benzene rings stabilize the cyclopropane ring The benzene rings are electron withdrawing and stabilize the transition state. Draw a structure showing an aromatic resonance term Include formal charges and lone pair electrons on the oxygen atom Devise an efficient synthesis of 1 -phenyl-1 -heptagon utilizing an electrophone aromatic substitution reaction as a key step Draw and select she missing reagents

Answer 1

(1) Consider the given reaction and draw the product as shown below: OH otoco H- Br Product In the above reaction carbonyl group reacts with HBr to form ionic compound in which carbon is having positive charge. The reaction occurs through the protonation of oxygen. The cyclopropenyl cation is stabilized as the ring become aromatic in nature due to presence of 2 pi electrons following Huckel (4n+2) pi electron rule, where n is zero. Hence, the reason for stability of the ionic product is that the product is stable aromatic cyclopropene. Hence, option second is correct. (2) Consider the structure of the aromatic resonance form of the given compound as shown below: Aromatic ion In the given structure the ring is containing 6 pi electrons and a carbonyl group therefore, the electron density from carbonyl double bond will shift towards the oxygen atom so that the ring become aromatic in nature containing 6 pi electrons.

In the given reaction, first step would be the Friedel craft acylation which result in the electrophilic addition on benzene ring in the presence of aluminium chloride which on reduction with NaBH4 results in the corresponding alcohol product as shown below: Missing reactant 1. AICI: 2. NaBH (missing reagent)