Chapter 12, Problem 12.28P

Interpretation Introduction

(a)

Interpretation:

How the given compound can be synthesized from an acyclic compound is to be shown.

Concept introduction:

Compounds containing a cyclopropyl ring can be synthesized from alkenes and alkynes. When an alkene or an alkyne is treated with a carbene ${\text{R}}_{\text{2}}\text{C:}$, the $\text{π}$ bond is replaced by a $-{\text{C(R}}_{\text{2}}\text{)}-$ bridge. This results in the introduction of a cyclopropyl ring on the substrate. The ‘R’ group(s) in the carbene may be hydrogen, a halogen or a combination of these.

A carbene is a highly reactive species and is generated in situ. Common methods are irradiating diazomethane with ultraviolet light, of treating a haloform (trihalomethane) with a strong base. The carbene adds to the double bond in a concerted reaction – the lone pair on the carbene forms a bond with one carbon of the double (or triple) bond and the $\text{π}$ bond pair simultaneously forms a bond to the carbene carbon.

Interpretation Introduction

(b)

Interpretation:

How the given compound can be synthesized from an acyclic compound is to be shown.

Concept introduction:

Compounds containing a cyclopropyl ring can be synthesized from alkenes and alkynes. When an alkene or an alkyne is treated with a carbene ${\text{R}}_{\text{2}}\text{C:}$, the $\text{π}$ bond is replaced by a $-{\text{C(R}}_{\text{2}}\text{)}-$ bridge. This results in the introduction of a cyclopropyl ring on the substrate. The ‘R’ group(s) in the carbene may be hydrogen, a halogen or a combination of these.

A carbene is a highly reactive species and is generated in situ. Common methods are irradiating diazomethane with ultraviolet light, of treating a haloform (trihalomethane) with a strong base. The carbene adds to the double bond in a concerted reaction – the lone pair on the carbene forms a bond with one carbon of the double (or triple) bond and the $\text{π}$ bond pair simultaneously forms a bond to the carbene carbon.