Dioxolane is a heterocyclic acetal with the chemical formula (CH2)2O2CH2. It is related to tetrahydrofuran (THF) by replacement of the methylene group (CH2) at the 2-position with an oxygen atom. The corresponding saturated 6-membered C4O2 rings are called . The 1,2-dioxolane (wherein the two oxygen centers are adjacent) is a organic peroxide. 1,3-dioxolane is used as a solvent and as a comonomer in .
As a class of compounds
Dioxolanes are a group of
containing the dioxolane ring. Dioxolanes can be prepared by
acetalization of
and
ketalization of
with
ethylene glycol.
(+)- cis-Dioxolane is the trivial name for which is a muscarinic acetylcholine receptor agonist.
Protecting groups
Organic compounds containing
sometimes need
protecting group so that they do not undergo reactions during transformations of other
that may be present. A variety of approaches to protection and deprotection of carbonyls
including as dioxolanes
are known. For example, consider the compound methyl cyclohexanone-4-carboxylate, where lithium aluminium hydride reduction will produce 4-hydroxymethylcyclohexanol. The ester functional group can be reduced without affecting the
ketone by protecting the ketone as a
ketal. The ketal is produced by acid catalysed reaction with
ethylene glycol, the reduction reaction carried out, and the protecting group removed by hydrolysis to produce 4-hydroxymethylcyclohexanone.
NaBArF4 can also be used for deprotection of acetal or ketal-protected carbonyl compounds.
- :PhCH(OCH2)2 + water ->\ce{NaBAr4}\text{30 PhCHO + ethylene glycol
Natural products
Neosporol is a
natural product that includes a 1,3-dioxolane moiety, and is an isomer of
sporol which has a 1,3-dioxane ring.
The
total synthesis of both compounds has been reported, and each includes a step in which a dioxolane system is formed using trifluoroperacetic acid (TFPAA), prepared by the hydrogen peroxide – urea method.
This method involves no water, so it gives a completely
anhydrous peracid,
necessary in this case as the presence of water would lead to unwanted
.
- + → + + urea
In the case of neosporol, a Prilezhaev reaction
A similar approach is used in the total synthesis of sporol, with the dioxolane ring later expanded to a dioxane system.
See also
External links
