A series of bi- and tricyclic 4,5-dihydropyrazoles have been studied by 1H n.m.r. and 13C n.m.r. spectroscopy and X-ray crystallography. They were synthesised by treating the corresponding mono-and dibenzylidenecycloalkanones and 2-benzylidene-3,4-dihydronaphthalen-1 (2H)-one with semicarbazide, which gave two diastereoisomers, and thiosemicarbazide, which gave only one. The 1H n.m.r. parameters allowed an unambiguous identification of the diastereoisomers and the configuration of one of the isomeric pairs was confirmed by 13C n.m.r. spectroscopy and X-ray crystallography. The crystallographic analysis shows that the six-membered rings assume an intermediate shape between the chair, half-chair and envelope forms, while the five-membered rings have a perfect envelope conformation with C(5) on the flap.
|Number of pages||6|
|Journal||Journal of the Chemical Society, Perkin Transactions 1|
|Publication status||Published - Jan 1 1985|
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