Benzisoxazole

1,2-Benzisoxazole is an aromatic organic compound with a molecular formula C7H5NO containing a benzene-fused isoxazole ring structure.[1][2] The compound itself has no common applications; however, functionalized benzisoxazoles and benzisoxazoyls have a variety of uses, including pharmaceutical drugs such as some antipsychotics (including risperidone, paliperidone, ocaperidone, and iloperidone) and the anticonvulsant zonisamide.

Not to be confused with 2,1-Benzisoxazole.
Benzisoxazole
Skeletal formula with numbering convention
Ball-and-stick molecular model
Space-filling molecular model
Names
Preferred IUPAC name
1,2-Benzoxazole
Other names
Benzo[d]isoxazole; Indoxazine
Identifiers
3D model (JSmol)
2154
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.005.440
EC Number
  • 205-983-1
UNII
  • InChI=1S/C7H5NO/c1-2-4-7-6(3-1)5-8-9-7/h1-5H checkY
    Key: KTZQTRPPVKQPFO-UHFFFAOYSA-N checkY
  • InChI=1/C7H5NO/c1-2-4-7-6(3-1)5-8-9-7/h1-5H
    Key: KTZQTRPPVKQPFO-UHFFFAOYAI
  • n2oc1ccccc1c2
Properties
C7H5NO
Molar mass 119.123 g·mol−1
Appearance Colorless liquid
Density 1.18 g/cm3
Boiling point 35 to 38 °C (95 to 100 °F; 308 to 311 K) (at 2.67 hPa)
101-102 °C (at 2 kPa)
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Flash point 58 °C (136 °F; 331 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

Its aromaticity makes it relatively stable;[3] however, it is only weakly basic.

Synthesis

Benzisoxazole may be prepared from inexpensive salicylaldehyde, via a base catalyzed room temperature reaction with hydroxylamine-O-sulfonic acid.[4]

Synthesis of 1,2-Benzisoxazol aus Salicylaldehyd und HOSA
Synthesis of 1,2-Benzisoxazol aus Salicylaldehyd und HOSA

Reactions

Kemp elimination

First reported by Daniel S. Kemp,[5][6][7] the relatively weak N-O bond can be cleaved by a strong base to yield a 2-hydroxybenzonitrile species.

See also
Structural isomers

References
  1. Katritzky, A. R.; Pozharskii, A. F. (2000). Handbook of Heterocyclic Chemistry (2nd ed.). Academic Press. ISBN 0080429882.
  2. Clayden, J.; Greeves, N.; Warren, S.; Wothers, P. (2001). Organic Chemistry. Oxford, Oxfordshire: Oxford University Press. ISBN 0-19-850346-6.
  3. Domene, Carmen; Jenneskens, Leonardus W.; Fowler, Patrick W. (2005). "Aromaticity of anthranil and its isomers, 1,2-benzisoxazole and benzoxazole". Tetrahedron Letters. 46 (23): 4077–4080. doi:10.1016/j.tetlet.2005.04.014. hdl:1874/14837. ISSN 0040-4039.
  4. Kemp, D.S.; Woodward, R.B. (1965). "The N-ethylbenzisoxazolium cation—I". Tetrahedron. 21 (11): 3019–3035. doi:10.1016/S0040-4020(01)96921-2. ISSN 0040-4020.
  5. Casey, Martha L.; Kemp, D. S.; Paul, Kenneth G.; Cox, Daniel D. (June 1973). "Physical organic chemistry of benzisoxazoles. I. Mechanism of the base-catalyzed decomposition of benzisoxazoles". The Journal of Organic Chemistry. 38 (13): 2294–2301. doi:10.1021/jo00953a006.
  6. Kemp, D. S.; Cox, Daniel D.; Paul, Kenneth G. (December 1975). "Physical organic chemistry of benzisoxazoles. IV. Origins and catalytic nature of the solvent rate acceleration for the decarboxylation of 3-carboxybenzisoxazoles". Journal of the American Chemical Society. 97 (25): 7312–7318. doi:10.1021/ja00858a018.
  7. Kemp, Daniel S. (April 1970). "Decarboxylation of benzisoxazole-3-carboxylic acids. Catalysis by extraction of possible relevance to the problem of enzymic mechanism". Journal of the American Chemical Society. 92 (8): 2553–2554. doi:10.1021/ja00711a061.
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