Dioxolane

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Dioxolane[1]
1,3-dioxolane-2D-skeletal.png
1,3-dioxolane-3D-balls.png
Names
IUPAC name
Dioxolane
Other names
1,3-dioxolane, formal glycol[2]
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.010.422
Properties
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)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Dioxolane is a heterocyclic acetal with the chemical formula (CH2)2O2CH2. It is related to tetrahydrofuran by interchange of one oxygen for a CH2 group. 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.

As a class of compounds[edit]

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.[3]

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[edit]

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[4] including as dioxolanes[5] 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-hydroxmethylcyclohexanone.

Acetal-protection-example.png

NaBArF4 can also be used for deprotection of acetal or ketal-protected carbonyl compounds.[4][5] For example, deprotection of 2-phenyl-1,3-dioxolane to benzaldehyde can be achieved in water in five minutes at 30 °C.[6]

PhCH(OCH2)2   +   H2O     PhCHO   +   HOCH2CH2OH

Neosporol[edit]

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.[7] 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.[8][9] This method involves no water, so it gives a completely anhydrous peracid,[10] necessary in this case as the presence of water would lead to unwanted side reactions.[8]

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

In the case of neosporol, a Prilezhaev reaction[11] 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.[8][9]

Neosporol epoxidation-rearrangement.png

A similar approach is used in the total synthesis of sporol, with the dioxolane ring later expanded to a dioxane system.[7]

See also[edit]

References[edit]

  1. ^ 1,3-Dioxolane at Sigma-Aldrich
  2. ^ formal glycol - PubChem Public Chemical Database
  3. ^ R. A. Daignault, E. L. Eliel (1973). "2-Cyclohexyloxyethanol (involves acetalisation of cyclohexanone)". Org. Synth. ; Coll. Vol., 5, p. 303 
  4. ^ a b Greene, Theodora W.; Wuts, Peter G. M. (1999). "Dimethyl acetals". Greene's Protective Groups in Organic Synthesis (3rd ed.). Wiley-Interscience. pp. 297–304, 724–727. ISBN 9780471160199. Archived from the original on December 3, 2016. Retrieved June 20, 2017. 
  5. ^ a b Greene, Theodora W.; Wuts, Peter G. M. (1999). "1,3-Dioxanes, 1,3-Dioxolanes". Greene's Protective Groups in Organic Synthesis (3rd ed.). Wiley-Interscience. pp. 308–322, 724–727. ISBN 9780471160199. Archived from the original on December 7, 2016. Retrieved June 20, 2017. 
  6. ^ Chang, Chih-Ching; Liao, Bei-Sih; Liu, Shiuh-Tzung (2007). "Deprotection of Acetals and Ketals in a Colloidal Suspension Generated by Sodium Tetrakis(3,5-trifluoromethylphenyl)borate in Water". Synlett. 2007 (2): 283–287. doi:10.1055/s-2007-968009. 
  7. ^ a b Pirrung, Michael C.; Morehead, Andrew T.; Young, Bruce G., eds. (2000). "10. Neosporol, Sporol". Part B: Bicyclic and Tricyclic Sesquiterpenes. The Total Synthesis of Natural Products. 11. John Wiley & Sons. pp. 222–224. ISBN 9780470129630. 
  8. ^ a b c Ziegler, Fredrick E.; Metcalf, Chester A.; Nangia, Ashwini; Schulte, Gayle (1993). "Structure and total synthesis of sporol and neosporol". J. Am. Chem. Soc. 115 (7): 2581–2589. doi:10.1021/ja00060a006. 
  9. ^ a b Caster, Kenneth C.; Rao, A. Somasekar; Mohan, H. Rama; McGrath, Nicholas A.; Brichacek, Matthew (2012). "Trifluoroperacetic Acid". e-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt254.pub2. 
  10. ^ Cooper, Mark S.; Heaney, Harry; Newbold, Amanda J.; Sanderson, William R. (1990). "Oxidation Reactions Using Urea–Hydrogen Peroxide; A Safe Alternative to Anhydrous Hydrogen Peroxide". Synlett. 1990 (9): 533–535. doi:10.1055/s-1990-21156. 
  11. ^ Hagen, Timothy J. (2007). "Prilezhaev reaction". In Li, Jie Jack; Corey, E. J. Name Reactions of Functional Group Transformations. John Wiley & Sons. pp. 274–281. ISBN 9780470176504. 

External links[edit]