Pyrazoline stereoisomers

The reaction of arylidenecyclonones with hydrazines proceeds with the formation of regio- and stereoisomers. Thus, treatment of bisbenzylidene-4-thiopyranones 66 with propylhydrazine 67 in boiling methanol yields mixtures of two isomeric pyrazolines 68 and 69, with 68 predominating [90] (Scheme 2.17). The amount of isomer 69 increases when X is S to SO and S02. 

RSaS stereoisomers.29 The 1,3-dipolar cycloaddition of [60]fullerene with diazomethane, nitrile oxide, and nitrone afforded fullereno-pyrazolines and -isoxazolines. These reactions were modelled at the B3LYP/6-31G(d,p)//AMl level and the reaction mechanisms, regiochemistry, and nature of addition were investigated.30... 

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