N. Mishriky et al., Regioselective synthesis of spiro[naphthalene-2(1H),3 '-[3H]pyrazol]-1-ones utilizing 1,3-dipolar cycloaddition of nitrilimines, J CHEM R-S, (1), 2000, pp. 2-3
1,3-Dipolar cycloaddition reaction of nitrilimines to a variety of 2-arylme
thylidene-3,4-dihydro-1-naphthalenones 1a-h afforded the corresponding spir
o[naphthalene-2(1 H),3'-[3H]pyrazol]-1-ones 3 and not the isomeric spiro[na
phthalene-2(1H),4'-[4H]pyrazol]-1-ones 4, in high regioselectivity. The str
ucture of the isolated products was established through different spectrosc
opic techniques and confirmed via HMBC.