Diazo
![Diazo compounds have two main Lewis structures in resonance: R2>C-–N+≡N and R2>CH=N+=N-](http://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/DiazoResonance.svg/300px-DiazoResonance.svg.png)
In organic chemistry, the diazo group is an organic moiety consisting of two linked nitrogen atoms at the terminal position. Overall charge-neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds or diazoalkanes[a] and are described by the general structural formula R2C=N+=N−. The simplest example of a diazo compound is diazomethane, CH2N2. Diazo compounds (R2C=N2) should not be confused with azo compounds (R−N=N−R) or with diazonium compounds (R−N+2).
Structure
The
Four
Compounds with the diazo moiety should be distinguished from
History
Diazo compounds were first produced by Peter Griess who had discovered a versatile new chemical reaction, as detailed in his 1858 paper "Preliminary notice on the influence of nitrous acid on aminonitro- and aminodinitrophenol."[2][3]
Synthesis
Several methods exist for the preparation of diazo compounds.[4][5]
From amines
Alpha-acceptor-substituted primary aliphatic amines R-CH2-NH2 (R = COOR, CN, CHO, COR) react with nitrous acid to generate the diazo compound.
From diazomethyl compounds
An example of an
By diazo transfer
In diazo transfer certain
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6c/DOXGON.png/220px-DOXGON.png)
The mechanism involves attack of the enolate at the terminal nitrogen, proton transfer, and expulsion of the anion of the sulfonamide. Use of the β-carbonyl aldehyde leads to a deformylative variant of the Regitz transfer, which is useful for the preparation of diazo compounds stabilized by only one carbonyl group.[13]
![](http://upload.wikimedia.org/wikipedia/commons/thumb/4/4b/Regitz.png/450px-Regitz.png)
From N-alkyl-N-nitroso compounds
Diazo compounds can be obtained in an
(The mechanism shown here is one possibility.[15] For an alternative mechanism for the analogous formation of diazomethane from an N-nitrososulfonamide, see the page on Diazald.)
From hydrazones
Reaction of a
From azides
One method is described for the synthesis of diazo compounds from
Reactions
In cycloadditions
Diazo compounds react as 1,3-dipoles in diazoalkane 1,3-dipolar cycloadditions.
As carbene precursors
Diazo compounds are used as precursors to
Diazo compounds are intermediates in the Bamford–Stevens reaction of tosylhydrazones to alkenes, again with a carbene intermediate:
In the Doyle–Kirmse reaction, certain diazo compounds react with allyl sulfides to the homoallyl sulfide. Intramolecular reactions of diazocarbonyl compounds provide access to cyclopropanes. In the Buchner ring expansion, diazo compounds react with aromatic rings with ring-expansion.
As nucleophile
The Buchner-Curtius-Schlotterbeck reaction yields ketones from aldehydes and aliphatic diazo compounds:
The reaction type is nucleophilic addition.
Occurrence in nature
Several families of naturally occurring products feature the diazo group. The
One
See also
Notes
- ^ The term diazoalkane is used by some authors to refer to any substituted diazomethane (i.e., all diazo compounds). However, other authors use the term to refer exclusively to diazo compounds with alkyl substituents that do not contain other functional groups (which would exclude compounds like diazo(diphenyl)methane or ethyl diazoacetate).
References
- ^ F.A. Carey R.J. Sundberg Advanced Organic Chemistry, 2nd Edition
- Oxford Dictionary of National Biography, Oxford University Press, 2004
- ^ Peter Griess (1858) "Vorläufige Notiz über die Einwirkung von salpetriger Säure auf Amidinitro- und Aminitrophenylsäure," (Preliminary notice of the reaction of nitrous acid with picramic acid and aminonitrophenol), Annalen der Chemie und Pharmacie, 106 : 123-125.
- OCLC 642506595
- ^ Example Organic Syntheses, Coll. Vol. 3, p.119 (1955); Vol. 26, p.13 (1946).Link
- ^ M. Regitz, Angew. Chem., 79, 786 (1967); Angew. Chem. Intern. Ed. Engl., 6, 733 (1967).
- ^ Organic Syntheses, Coll. Vol. 5, p.179 (1973); Vol. 48, p.36 (1968). Link
- ^ Organic Syntheses, Coll. Vol. 6, p.414 (1988); Vol. 59, p.66 (1979). Link
- ISBN 978-0-470-84289-8.
- .
- .
- OCLC 850164343.
- ^ Example: Organic Syntheses, Coll. Vol. 6, p.981 (1988); Vol. 57, p.95 (1977). Link
- )
- ^ Organic Syntheses, Coll. Vol. 6, p.392 (1988); Vol. 50, p.27 (1970). Link
- ^ Organic Syntheses, Coll. Vol. 5, p.258 (1973); Vol. 49, p.22 (1969). Link
- ^ Organic Syntheses, Coll. Vol. 7, p.438 (1990); Vol. 64, p.207 (1986).http://www.orgsyn.org/orgsyn/prep.asp?prep=CV7P0438
- PMID 17105273.
- ^ Elusive Natural Product Is Synthesized Stu Borman Chemical & Engineering News October 31, 2006 Link Archived 2008-08-28 at the Wayback Machine.
- ^ Organic Syntheses, Coll. Vol. 6, p.913 (1988); Vol. 50, p.94 (1970).Link
- PMID 30120394.