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

SYNTHESIS OF NITRONATES 461
(39) (see Scheme 3.33) or are directly transformed into target nitronates (35c)
according to the Mitsunobu procedure (see Scheme 3.34).
If trinitromethane (R=X=NO2) is used as starting compound (40), the steps
(1) to (3) give rise to product (40), from which cyclic nitronate (35 d) can be
prepared by denitration of the C(NO2)3 group and cyclization of bromide (41)
(Eq. 5).
There are other synthetic routes to halides similar to compounds (39), which
are direct precursors of six-membered cyclic nitronates (35) (Scheme 3.36).
Sometimes, the nitro group can be introduced via nitration into functionalized
halo-containing compounds at the α position with respect to the functional group
(91) (Eq. 1).
Selective C-alkylation of the Na[CH(NO2)SO2Ph] salt with 1-chloro-3-iodopropane
(Eq. 2) followed by cyclization of product (39b) was documented (70).
Interesting data were reported in Reference 98 on the transformation of the
sulfuric acid salt of amine under conditions of nitrosation (Scheme 3.37).
Apparently, this reaction initially produces unstable diazo compound, which
gives cation A.
The latter is involved in the intramolecular alkylation of one of the nitro
groups accompanied by elimination of the nitronium cation. It was not rigorously
established whether the reaction afforded six-membered cyclic nitronate (35 d) or
NO 2
NO 2
Cl
Cl I
NO 2
NO 2
CN C5H11ONO2/KOBu Cl
t
DMF
Na[CHNO 2(SO 2Ph)]
NH 2·H 2SO 4 NaNO2/NaHCO3
Cl
Scheme 3.36
NO 2
NO2
Scheme 3.37
A
39b
NO 2
39a
NO 2
NO2
+
NO 2
CN
SO 2Ph
−NO2 +
(1)
(2)
NO 2 NO 2
O N
35d
or
NO2
O N
24j
O
O
NO 2