Stick model of a 1,2-oxaphosphetane that has been isolated and characterised by X-ray crystallography.[1]

An oxaphosphetane is a molecule containing a four-membered ring with one phosphorus, one oxygen and two carbon atoms. In a 1,2-oxaphosphetane phosphorus is bonded directly to oxygen, whereas a 1,3-oxaphosphetane has the phosphorus and oxygen atoms at opposite corners.

1,2-Oxaphosphetanes are rarely isolated but are important intermediates in the Wittig reaction and related reactions such as the Seyferth–Gilbert homologation and the Horner–Wadsworth–Emmons reaction.[2] Edwin Vedejs's NMR studies first revealed the importance of oxaphosphetanes in the mechanism of the Wittig reaction in the 1970s.[3][4]

In 2005 the first isolation of 1,2-Oxaphosphetanes (typical Wittig intermediates) was reported.[5] One of the compounds was characterized by X-ray crystallography and NMR. Although relatively stable, thermal decomposition of these oxaphosphetanes gave a phosphonium salt, which slowly dissociated to the Wittig reaction starting materials, the carbonyl and olefin compounds.

References

  1. ^ M. Hamaguchi; Y. Iyamaa; E. Mochizukia; T. Oshima (2005). "First isolation and characterization of 1,2-oxaphosphetanes with three phenyl groups at the phosphorus atom in typical Wittig reaction using cyclopropylidenetriphenylphosphorane". Tetrahedron Letters. 46 (51): 8949–8952. doi:10.1016/j.tetlet.2005.10.086.
  2. ^ Byrne, Peter A.; Gilheany, Declan G. (2013). "The modern interpretation of the Wittig reaction mechanism". Chemical Society Reviews. 42 (16): 6670–6696. doi:10.1039/C3CS60105F. hdl:10197/4939. PMID 23673458.
  3. ^ Vedejs E (30 July 2004). "Studies in Heteroelement-Based Synthesis". The Journal of Organic Chemistry. 69 (16): 5159–5167. doi:10.1021/jo049360l. PMID 15287757.
  4. ^ "Memorial Resolution of the Faculty of the University of Wisconsin-Madison" (PDF). University of Wisconsin-Madison. Archived from the original (PDF) on 9 May 2020. Retrieved 9 May 2020.
  5. ^ M. Hamaguchi; Y. Iyamaa; E. Mochizukia; T. Oshima (2005). "First isolation and characterization of 1,2-oxaphosphetanes with three phenyl groups at the phosphorus atom in typical Wittig reaction using cyclopropylidenetriphenylphosphorane". Tetrahedron Letters. 46 (51): 8949–8952. doi:10.1016/j.tetlet.2005.10.086.
Allikas: https://en.wikipedia.org/wiki/Oxaphosphetane
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