- Interplay of theory and experiment: Reversal of the torquoselectivity of the electrocyclic ring opening of 3-acetylcyclobutene by a Lewis acid
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Theoretical predictions, accompanied by firm experimental verification, are presented on the "torquoselectivity" of the thermal ring opening of 3-acetylcyclobutene (1). 3-Acetylcyclobutene was synthesized from commercially available 1,1-cyclobutanedicarboxylic acid. Thermolysis of 3-acetylcyclobutene resulted in a mixture of E- and Z-dienes with a slight preference for the E-diene. This preference was reversed by the Lewis acid, ZnI2, as predicted from theoretical calculations.
- Niwayama, Satomi
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- Synthesis and Applications of Polysubstituted Bicyclo[1.1.0]butanes
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Bicyclo[1.1.0]butanes (BCBs) are valuable substrates in the “strain release” synthesis of polysubstituted four-membered ring systems, with applications including bioconjugation agents. The introduction of substituents onto the BCB bridges is challenging d
- Anderson, Edward A.,McNamee, Ryan E.,Thompson, Amber L.
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p. 21246 - 21251
(2021/12/27)
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- Expedient synthesis of cis- and trans-3-aminocyclobutanecarboxylic acids
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An expedient approach to cis- and trans-3-aminocyclobutanecarboxylic acids was developed starting from 1,1-cyclobutanedicarboxylic acid. Stereochemistry of the title compounds was established by nuclear Overhauser effect spectroscopy experiments.
- Radchenko, Dmytro S.,Tkachenko, Anton,Grygorenko, Oleksandr O.,Komarov, Igor V.
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p. 1644 - 1649
(2011/06/23)
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- Stereochemistry of the thermal conversion of 1-vinyl-2,3-cis-dideuteriocyclobutane to butadiene and 1,2-dideuterioethylenes
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This study has examined the stereochemistry of the decomposition at 900-1000 K in a single-pulse shock tube of 1-vinyl-2,3-cis-dideuteriocyclobutane to ethylenes and buta-1,3-dienes. The deuterated ethylenes formed during the decomposition, CHD=CH2, (E)-CHD=CHD, and (Z)-CHD=CHD, were quantified via two independent techniques, FTIR and IR absorption spectroscopy using a tunable diode laser spectrometer. The results of both analyses indicated that equal amounts of (E)-CHD=CHD and (Z)-CHD=CHD were formed from the cis-labeled reactant. In an earlier shock tube study of the decomposition at 1000-1200 K of two deuterium-labeled cyclohexenes to ethylenes plus buta-1,3-dienes, a pathway via a vinylcyclobutane intermediate was implicated in a significant fraction of the decomposition events; the measured ratios of (E)-CHD=CHD to (Z)-CHD=CHD in that study were consistent with a complex mechanistic model in which the stereochemistry of deuterium labels in the cyclohexene reactant was lost in ethylene products formed via vinylcyclobutane. The present results provide additional support for that model.
- Lewis, David K.,Hutchinson, Avery,Lever, Steven J.,Spaulding, Eric L.,Bonacorsi Jr., Samuel J.,Baldwin, John E.
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p. 233 - 237
(2007/10/03)
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- SYNTHESIS OF SQ-32,829, A NEW NUCLEOSIDE ANTIVIRAL AGENT
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The guanine-containing cyclobutane nucleoside analog SQ-32,829 (1) was synthesized in 8 steps from 1,1-cyclobutanedicarboxylic acid(3).
- Jacobs, G. A.,Tino, J. A.,Zahler, R.
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p. 6955 - 6958
(2007/10/02)
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- Prediction and Experimental Verification of the Stereoselective Electrocyclization of 3-Formylcyclobutene
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3-Formylcyclobutene has been synthesized from cyclobutene-1, 1-dicarboxylic acid; it opens at 25-70 deg C with an activation energy of 27 +/- 1 kcal/mol to give exclusively (> 98percent) the Z product, in accord with predictions.
- Rudolf, Klaus,Spellmeyer, David C.,Houk, K. N.
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p. 3708 - 3710
(2007/10/02)
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- 6-(Substituted-cycloalkylcarboxamide) penicillanic acids
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Penicillins of the formula SPC1 Or a pharmaceutically-acceptable, nontoxic salt thereof, Wherein R1 and R2 are the same or different and each is hydrogen, fluorine, chlorine or bromine; or when R2 is hydrogen, R1 can also be cyano, hydroxyl, azido, amino or nitro; or R1 and R2 are bonded to a ring carbon atom and constitute a single oxygen atom; R3 is hydrogen, methyl, chlorine, bromine, cyano, methoxy or carboxyl; and n is 2 to 7; Are useful for their antibacterial activity.
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