Chapter 28, Problem 28.42AP

Interpretation Introduction

Interpretation:

Certain black bugs of the order Hemiptera, generally observed in the tropical regions of India immediately after the rainy season, give off a characteristic nauseating smell whenever they are disturbed or crushed. Substance A, the compound causing the odor, can be obtained either by extracting the bugs with petroleum ether (which no doubt disturbs them greatly), or it can be prepared by heating the compound below at 170 – 180 °C for a short time. The structure of compound A is to be stated.

Concept introduction:

Sigmatropic reaction can be described as the migration of allylic sigma bond at one end of the π-electron system to the other end of the π-electron system as an uncatalyzed intramolecular reaction. In some cases, Lewis acid catalysts can also be applied. Though, the position of π-bond is changed in Sigmatropic reaction, the total number of π-bonds remain unchanged. The sigma bond can be cleaved at the middle or at the end of the π-system. The formation of sigma bond at 3, 3-position of a 1, 5-diene is called as cope rearrangement. Notably, [3, 3] sigmatropic reaction of allyl vinyl ether is termed as Claisen rearrangement.