Thermolysis of trifluoromethyl-containing vinyldiazocarbonyl compounds and X-ray crystal structure analysis of unexpected reaction products

• Fluorinated α-vinyl-α-diazocarbonyl compounds (F-VDC) 1, 2 do not produce pyrazoles.
• Thermolysis of F-vinyldiazoacetate 1 gives bis-CF3-substituted fused bicyclooctadiene.
• F-Vinyldiazoketone 2 upon heating produces bis-CF3-substituted cycloheptatriene.
• The crystal structure of both products was unambiguously established by X-ray analysis.
• Different reactivity of F- and H-VDC is caused by their dissimilar configuration.

Two unusual compounds, 1,3a,6,6a-tetrahydro-3a,6a-bis(trifluoromethyl)-cyclopenta[c]pyrazol-3,4,5,6-tetracarboxylic acid tetramethyl ester (C16H14N2O8F6) (3) and 2-acetyl-5,7-bis(trifluoromethyl)-4-methyl-3-methoxy-2,4,6-cycloheptatrienecarboxylic acid methyl ester (C14H11F6O3) (4), were obtained from thermolysis of 3-trifluoromethyl-substituted vinyldiazocarbonyl compounds. The crystal structures of the products were determined as part of a larger comparison study on the thermal and Rh(II)-catalyzed reactions of F- and H-vinyldiazocarbonyl compounds. The resulting structures provide the first crystallographic characterization of bis(trifluoromethyl)substituted compounds of this kind. The pure compounds with all-carbon (4) and half-heterocyclic (3) skeletons are composed of a seven- and two-annulated five-membered rings in folded butterfly and envelope conformations, respectively.

Thermal reactions of fluoroalkyl-containing α-vinyl-α-diazoketone and α-diazoacetate proceed quite differently than those of the relevant non-fluorinated analogues and instead of pyrazoles produce bis(trifluoromethyl)substituted cycloheptatriene and diazabicyclooctadiene derivatives, respectively.Figure optionsDownload as PowerPoint slide