Dioxolane

This article is about 1,3-dioxolane. For the other dioxolane isomer, see 1,2-dioxolane.

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 dioxanes. The isomeric 1,2-dioxolane (wherein the two oxygen centers are adjacent) is a peroxide. 1,3-dioxolane is used as a solvent and as a comonomer in polyacetals.

Dioxolane^[1]

Names
Preferred IUPAC name 1,3-Dioxolane[2]
Systematic IUPAC name 1,3-Dioxacyclopentane
Other names Dioxolane 5-Crown-2 Formal glycol[3]
Identifiers
CAS Number	646-06-0 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:87597 Y
ChEMBL	ChEMBL3187281
ChemSpider	12066 Y
ECHA InfoCard	100.010.422
EC Number	211-463-5
PubChem CID	12586
UNII	Y57RBG19JL Y
UN number	1166
CompTox Dashboard (EPA)	DTXSID4027284
InChI InChI=1S/C3H6O2/c1-2-4-5-3-1/h1-3H2 Y Key: SNQXJPARXFUULZ-UHFFFAOYSA-N Y InChI=1/C3H6O2/c1-2-4-5-3-1/h1-3H2 Key: SNQXJPARXFUULZ-UHFFFAOYAS
SMILES O1CCOC1
Properties
Chemical formula	C3H6O2
Molar mass	74.08 g/mol
Density	1.06 g/cm3
Melting point	−95 °C (−139 °F; 178 K)
Boiling point	75 °C (167 °F; 348 K)
Hazards
GHS labelling:[4]
Pictograms
Signal word	Danger
Hazard statements	H225
Precautionary statements	P210, P233, P240, P241, P242, P243, P280, P303+P361+P353, P370+P378, P403+P235, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

As a class of compounds

Dioxolanes are a group of organic compounds containing the dioxolane ring. Dioxolanes can be prepared by acetalization of aldehydes and ketalization of ketones with ethylene glycol.^[5]

synthesis of dioxolane group

(+)-cis-Dioxolane is the trivial name for L-(+)-cis-2-methyl-4-trimethylammoniummethyl-1,3-dioxolane iodide which is a muscarinic acetylcholine receptor agonist.

Protecting groups

Organic compounds containing carbonyl groups sometimes need protection so that they do not undergo reactions during transformations of other functional groups that may be present. A variety of approaches to protection and deprotection of carbonyls^[6] including as dioxolanes^[7] 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.^[6][7] For example, deprotection of 2-phenyl-1,3-dioxolane to benzaldehyde can be achieved in water in five minutes at 30 °C.^[8]

PhCH(OCH₂)₂   +   H₂O   ${\displaystyle {\ce {->[{\ce {NaBAr4}}][{\text{30 °C / 5 min}}]}}}$ PhCHO + HOCH₂CH₂OH

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.^[9] 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.^[10][11] This method involves no water, so it gives a completely anhydrous peracid,^[12] necessary in this case as the presence of water would lead to unwanted side reactions.^[10]

CF
₃COOCOCF
₃   +   H
₂O
₂•CO(NH
₂)
₂   →   CF
₃COOOH   +   CF
₃COOH   +   CO(NH
₂)
₂

In the case of neosporol, a Prilezhaev reaction^[13] with trifluoroperacetic acid is used to convert a suitable allyl alcohol precursor to an epoxide, which then undergoes a ring-expansion reaction with a proximate carbonyl functional group to form the dioxolane ring.^[10][11]

A similar approach is used in the total synthesis of sporol, with the dioxolane ring later expanded to a dioxane system.^[9]

See also

• Dioxane