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Chemoselectivity and Conformational Analysis of the Reaction of 2‐Acetylcycloalkanones with Benzohydrazide: Synthesis and Reduction of 1‐Aroylcycloalkapyrazole Derivatives
Author(s) -
Tsoleridis Constantinos A.,
StephanidouStephanatou Julia,
Zika Chara,
Pozarentzi Minothora,
Alevizopoulos Stephanos
Publication year - 2003
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200390035
Subject(s) - chemistry , chemoselectivity , dept , derivative (finance) , two dimensional nuclear magnetic resonance spectroscopy , indazole , stereochemistry , carbon 13 nmr , medicinal chemistry , proton nmr , organic chemistry , catalysis , financial economics , economics
From the reaction of 2‐acetylcyclopentanone and 2‐acetyl‐2‐methylcyclopentanone with benzohydrazide, the 1‐benzoyl‐6a‐hydroxycyclopentapyrazole derivatives 2a and 2b were obtained as the only reaction products, whereas from the reaction of 2‐acetylcyclohexanone an epimeric cis/trans mixture of the 2‐benzoyl‐3‐hydroxy‐2 H ‐indazole derivative 3c was formed. The dehydration of the isolated compounds 2a and 3c , as well as the NaBH 4 and NaBH 3 CN reduction products of 2a were studied. The structural assignments of the compounds derived were established by analysis of their NMR spectra ( 1 H, 13 C, DEPT, COSY, NOESY, HETCOR CH, and COLOC CH). The chemoselectivity of the reactions of 1a and 1c with benzohydrazide was studied by conformational analysis with MM2 and semiempirical (AM1 and PM3) MO calculations.