The correct answer is E.
The synthesis of cyclopropane via addition to the double bond in an
alkene is accomplished by reaction with methylene, H2C:,
an example of a class of compounds known as carbenes in which carbon forms
two single bonds to make a neutral molecule. (Notice the lone pair of electrons
on the carbon atom.) This reactive intermediate is most commonly formed by
the heat- or light-induced decomposition of diazomethane, as shown in choice
E. The lone pair of electrons on the carbene intermediate are used together
with the electrons of the alkene to form the two new single bonds in the
cyclopropane product. (An alternative route to cyclopropane synthesis involves
reacting diiodomethane and a zinc-copper couple to generate a carbene-like
species called a carbenoid which will add a methylene group to the double
bond.)
(A)
Distortion. This will not produce the desired
product.
(B)
Distortion. This will not produce the desired
product.
(C)
Distortion. These reactants will produce
an addition with a methoxy group attaching to the second or third carbon.
(D)
Distortion. This will not produce the desired
product.
