Wittig-oxaphosphetane-from-xtal-2005-3D-sticks

An oxaphosphetane is a

molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

containing a four-membered ring with one

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

, one

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

and two

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

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 The Wittig reaction or Wittig olefination is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide called a Wittig reagent. Wittig reactions are most commonly used to convert aldehydes and ketones to alkenes. Most o ...

and related reactions such as the

Seyferth–Gilbert homologation The Seyferth–Gilbert homologation is a chemical reaction of an aryl ketone 1 (or aldehyde) with dimethyl (diazomethyl)phosphonate 2 and potassium tert-butoxide to give substituted alkynes 3. Dimethyl (diazomethyl)phosphonate 2 is often called th ...

and the

Horner–Wadsworth–Emmons reaction The Horner–Wadsworth–Emmons (HWE) reaction is a chemical reaction used in organic chemistry of stabilized phosphonate carbanions with aldehydes (or ketones) to produce predominantly E-alkenes. In 1958, Leopold Horner published a modifie ...

. Edwin Vedejs's

NMR Nuclear magnetic resonance (NMR) is a physical phenomenon in which atomic nucleus, nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near and far field, near field) and respond by producing ...

studies first revealed the importance of oxaphosphetanes in the mechanism of the Wittig reaction in the 1970s. In 2005 the first isolation of 1,2-Oxaphosphetanes (typical Wittig intermediates) was reported. One of the compounds was characterized by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

and

. Although relatively stable, thermal decomposition of these oxaphosphetanes gave a phosphonium salt, which slowly dissociated to the

starting materials, the carbonyl and olefin compounds.

References

{{Reflist Phosphorus heterocycles Oxygen heterocycles Four-membered rings