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

RCHO + +
NH2
n = 1, 2
R′
H
N
O
R
HO
N
O
O
( )n
( )n
NO 2
REACTIONS OF NITRILE OXIDES 75
NO 2
POCl 3, Et 3N
+ R′NC
R′
H
N
354 355
BuHN
O
Scheme 1.38
356
CHCl 3
N O
O
R
R′
R = H, Me, Et, Pr, Ph, CHMe 2
R′ = H, Me, decyl, Ph
The intramolecular cycloaddition reactions of the nitrile oxides 357 (n = 1, 2,
3, 9), obtained in situ from the 2,5-difunctional furan hydroximoyl chlorides or
nitro compounds (415) has speciÞc features because of the 2,5-arrangement of
two open chains bearing acetylenic and fulminic moieties. Only with 357 (n = 3)
is the expected furanoisoxazolophane 358 formed, in acceptable yield. Compound
357 (n = 9) gives a complex product mixture whereas 357 (n = 1, 2) gives rise
to the exclusive reaction of the dipole with a double bond of the furan system.
HC
O
1.3.5. Miscelaneous
O
357
O(CH2)nC
N + O −
O
O
MeOH
O
358
R
O
N
O
( ) n
O (CH2) 2
N
Reactions other than those discussed in subsections 1.3.1. to 1.3.4. are presented
here. Transformations of nitrile oxides by the action of reductive agents and
N
O