Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis : Novel ...

436 NITRONATES
One of the processes most generally used for the synthesis of nitrones is based
on reduction of AN to hydroxylamines followed by oxidation of the resulting
intermediates. In this process, the nitrogen atom of the nitro group remains in
the target nitrones. Another possible approach to the synthesis of nitrones from
AN, which involves the replacement of the nitrogen atom that is present in AN,
will be described later in this chapter.
Therefore, AN can be considered as convenient nearest precursors of nitrile
oxides, nitrones, and nitronates.
REFERENCES
1. Seebach D, Colwin EW, Lehr F, Weller T. Chimia 1979; 33: 1.
2. Tartakovsky VA. Bull. Acad. Sci. USSR, Div. Chem. Sci. 1984; 33: 147–155 (165–173
russ.).
3. Torssell KBG. Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis, VCH
Publishers, New York, 1988.
4. Ono N. “The Nitro Group in Organic Synthesis”, Wiley-VCH, New York, 2001.
5. Denmark SE, Cottell JJ. “The Chemistry of Heterocyclic Compounds, Vol. 59: Synthetic
Applications of 1,3-dipolar Cycloaddition Chemistry Toward Heterocycles and Natural
Products”, John Wiley & Sons, pp 83–167, 2002.
3.2. SYNTHESIS OF NITRONATES
Four general approaches to the synthesis of nitronates from AN are known
(Scheme 3.1).
The Þrst most commonly used approach (path a) involves the direct interaction
of AN with electrophilic reagents. In this case, the most fundamental
property of AN, that is, their ability to act as ambident nucleophiles in organic
reactions, is exploited. To synthesize nitronates, it is necessary that AN behave
H
C
NO2 AN
E +
(a)
(b)
(c)
for AN with C n≥C 2
(d)
O
C N [E – Alk, COR, Si, B