83922-59-2Relevant academic research and scientific papers
Reaction of a Highly Spiro-activated Electrophilic Cyclopropane with Pyridines; an Unusual Solvent Effect on Reaction Rate
Ohkata, Katsuo,Nagai, Takashi,Tamaru, Akira,Hanafusa, Terukiyo
, p. 43 - 48 (1986)
The kinetics of the reaction of 3,3,10,10-tetramethyldispirotridecane-1,5,8,12-tetraone (1) with pyridine was studied in various pure solvents (protic and aprotic).Although this reaction afforded a polar zwitterion , the solvent effect on the reaction rate was not as remarkable as that in the Menschutkin reaction; it was related to Gutmann's DN parameters rather than to the Dimroth-Reichardt ET values.The multiparameter analysis approach according to the Krygowski-Fawcett model in aprotic solvents and the Taft-Kamlet model in protic solvents was successful, giving log k2 = -8.82 X E-3ET - 17.4 X E-3DN - 3.36 (r = 0.927; n = 8) and log k2 = -0.734α + 0.162β - 3.15 (r = 0.941; n = 6), respectively.Mechanisms are discussed.
Reaction of a Highly Spiro-activated Electrophilic Cyclopropane with Pyridines. The Substituent Effect on the Reaction Rate
Ohkata, Katsuo,Nagai, Takashi,Tamaru, Akira,Nandate, Masa-aki,Hanafusa, Terukiyo
, p. 1255 - 1260 (2007/10/02)
The kinetics of the reactions of 3,3,10,10-tetramethyldispirotrideca-1,5,8,12-tetraone (7) with a series of substituted pyridines were investigated.The compound underwent well behaved second-order reactions with nucleophiles to afford the polar zwitterionic products (9).Values of log k in acetonitrile fall on a straight line when plotted against the pKa values of a series of 3- or 4-substituted pyridines and exhibit a Broensted slope of 0.24.Methyl substitution in the neighbourhood of the reaction centre in the substrate or a nucleophile produced a fall in reactivity to some degree (1/2-1/10).These results together with an unusual solvent effect are interpreted by a preassociative mechanism in which a polar encounter complex is formed prior to the cyclopropane ring opening to give the final product (9).
Reaction of a Highly Spiro-activated Cyclopropane with Pyridines. A Novel Intramolecular Charge Transfer Interaction of the Product
Ohkata, Katsuo,Tamaru, Akira,Nagai, Takashi,Hanafusa, Terukiyo
, p. 499 - 504 (2007/10/02)
The reaction of 3,3,10,10-tetramethyldispirotrideca-1,5,8,12-tetraone (1) with pyridines afforded a yellow crystalline product under very mild conditions.The structure of the product was assigned as a derivative of the pyridinium β-keto-enolate (2a) in which the cyclopropane ring of (1) is cleaved by heterolysis giving a β-ketoenolate anion.In its electronic spectrum the absorption maximum at longer wavelength (charge transfer band) for (2a) showed solvatochromic shifts.The transition energies (Ect) of (2a) measured in various solvents give linear plots against the Kosower Z values and Taft-Kamlet α-scales, with slopes of 0.62 and 15.70, respectively.Also, there is a linear relationship between Ect and the Hammett ?-value for each substituent of the heteroaromatic ring in (2a-g), the ρ-value being -16.8.The structure and properties of (2a) have been described from these results.
