Oxetane
Oxetane, or 1,3-propylene oxide, is a heterocyclic organic compound with the molecular formula Template:Chem/link, having a four-membered ring with three carbon atoms and one oxygen atom.
The term "an oxetane" or "oxetanes" refer to any organic compound containing the oxetane ring.
Production
A typical well-known method of preparation is the reaction of potassium hydroxide with 3-chloropropyl acetate at 150 °C:[1]
Yield of oxetane made this way is c. 40%, as the synthesis can lead to a variety of by-products including water, potassium chloride, and potassium acetate.
Another possible reaction to form an oxetane ring is the Paternò–Büchi reaction. The oxetane ring can also be formed through diol cyclizationTemplate:Sfn as well as through decarboxylation of a six-membered cyclic carbonate.Script error: No such module "Unsubst".
Derivatives
More than a hundred different oxetanes have been synthesized.Script error: No such module "Unsubst". Functional groups can be added into any desired position in the oxetane ring, including fully fluorinated (perfluorinated) and fully deuterated analogues. Major examples are:
| Name | Structure | Boiling point, Bp [°C] |
|---|---|---|
| 3,3-Bis(chloromethyl)oxetane | File:Bis(chloromethyl)oxetane.svg | 198[2] |
| 3,3-Bis(azidomethyl)oxetane | File:3,3-Bis(azidomethyl)oxetane.svg | 165[3] |
| 2-Methyloxetane | File:2-Methyloxetane.png | 60Script error: No such module "Unsubst". |
| 3-Methyloxetane | File:3-Methyloxetane.png | 67Script error: No such module "Unsubst". |
| 3-Azidooxetane | File:3-Azidooxetane.png | 122[4] |
| 3-Nitrooxetane | File:3-Nitrooxetane.png | 195[5] |
| 3,3-Dimethyloxetane | File:3,3-dimethyloxetane.png | 80Script error: No such module "Unsubst". |
| 3,3-Dinitrooxetane | File:3,3-Dinitrooxetane.png | – |
oxetane.svg){kind=link}
oxetane.svg){kind=link}
Taxol
Paclitaxel (Taxol) is an example of a natural product containing an oxetane ring. Taxol has become a major point of interest among researchers due to its unusual structure and success in the involvement of cancer treatment.[6] The attached oxetane ring is an important feature that is used for the binding of microtubules in structure activity; however little is known about how the reaction is catalyzed in nature, which creates a challenge for scientists trying to synthesize the product.[6]
Reactions
Oxetanes are less reactive than epoxides, and generally unreactive in basic conditions,Template:Sfn although Grignard reagents at elevated temperaturesTemplate:Sfn and complex hydrides will cleave them.Template:Sfn However, the ring strain does make them much more reactive than larger rings,Template:Sfn and oxetanes decompose in the presence of even mildly acidic nucleophiles.[7] In non-nucleophilic acids, they mainly isomerize to allyl alcohols.Template:Sfn
Noble metals tend to catalyze isomerization to a carbonyl.Template:Sfn
In industry, the parent compound, oxetane polymerizes to polyoxetane in the presence of a dry acid catalyst,[8] although the compound was described in 1967 as "rarely polymerized commercially".Template:Sfn
See also
- β-Propiolactone or 2-oxetanone.
- 3-Oxetanone
References
<templatestyles src="Reflist/styles.css" />
- ↑ Script error: No such module "Citation/CS1".; Script error: No such module "citation/CS1"..
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ a b Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Penczek & Penczek (1963), "Kinetics and mechanism of heterogeneous polymerization of 3,3-bis(chloromethyl)oxetane catalyzed by gaseous BF3" in Die Makromolekuläre Chemie. Wiley.
Script error: No such module "Check for unknown parameters".