1,3-Dipolar cycloaddition of E-2-arylidene-1-indanones 1a-h and Z- aurones 3a-c with diazomethane provided trans-spiro-1-pyrazolines 2a-h and 4a-c, respectively, as sole products. However, the same cycloaddition of Z- 1-thioaurones 5a-f afforded a mixture of Z-α-methyl-1-thioaurones 6a-f and trans-cyclopropane derivatives 7a-f as a result of the spontaneous denitrogenation of the initially formed 1-pyrazolines. Similar reaction of Z- 2-arylidene-2,3-dihydro-1H-indol-3-ones 8a,b and diazomethane yielded trans- cyclopropanes 9a,b. Structure and stereochemistry of the compounds synthesized have been elucidated by nmr spectroscopic measurements.
ASJC Scopus subject areas
- Organic Chemistry