Comportement particulier d'arylidènebenzothiazinonedioxydes dans les cycloadditions [3 + 2]. Compétition entre sites dipolarophiliques. Évolution des cycloadduits

Abstract

The reaction of diphenylnitrilimine with some arylidenebenzothiazinone dioxides leads to a mixture of two products that were isolated by chromatography. Spectroscopic data (infrared, nuclear magnetic resonance) and a radiocrystallographic study illustrate a competition between the two dipolarophilic sites in dipolar cycloaddition.

Regio‐ and stereoselective synthesis of spiro[1‐benzothiepine‐4(5h), 3′(3h)‐pyrazol]‐5‐ones

“…The pyrazoline H-4' is recognized as a sharp singlet signal at = 5.04-5.44 region. The appearance of this signal at the mentioned chemical shift value supports the isolation of 5 [40,41], where the other presumed regioisomeric form 6 used to reveal its characteristic H-3' signal at a chemical shift value downfield than >5.6 [42]. 13 C-NMR (on-resonance & APT) spectra of 5g "as a representative example" adds a good support for the established structure, where it reveals the two benzothiepine methylene carbons at = 28.89, 32.06, in addition to the methoxy and carbonyl carbons at = 55.08, 204.65, respectively.…”

Facile Regioselective Synthesis of 1,2,6,8-Tetraazaspiro[4.4]nona-2,6-dien-9-ones

“…In addition, the 'H N M R spectra exhibit a singlet signal at ((3) 5.32-5.38 assignable for the m ethine H-4. The appearance of this signal exclude the presence of the o th e r regio-isom er 5 [22][23][24], 13C N M R spectrum of 4c, as a representative exam ple, supports the proposed structure, since it exhibits the m ethine carbon (C-4) at d 65.3 and the spiro-C (C-5) at (3 92.2 in addition to the o th er skeletal carbons. These observed chem ical shift values are consistent with o th e r similar structures [24].…”

Microwave-assisted synthesis and in-vitro anti-tumor activity of 1,3,4-triaryl-5-N-arylpyrazole-carboxamides

“…The elemental analysis and mass spectrum (M þ 415 m/e) of the reaction product were compatible with the molecular formula C 28 H 21 N 3 O but not with the expected spiropyrazoline cycloadduct structure 6a or 9a having the molecular formula C 35 H 26 N 4 OS. The 1 H NMR spectrum of the obtained compound showed no signals due to the aliphatic pyrazoline-4-CH proton (typically d 4.7e5.1) [39,40] or the pyrazoline-5-CH proton (typically d 5.6) [41] which excluded the possible spiropyrazoline structures 6 and 9, respectively. The 13 C NMR spectrum of the product was free of any aliphatic CH.…”