“…The most stable dialkylcarbene found was a OH-NO 2 substituted derivative demonstrating increased singlet stabilization of 158.2 kJ mol -1 . Is there any stabilization seen for the corresponding dispiroalkanes?-spectroscopic evidence for slight aromatic stabilization in pentacyclopropylcyclopentane (alternatively called [5]-rotane) has been suggested [47]. We note now that the enthalpy of formation of the related species [3]-and [4]-rotane, as well as some other ''triangulanes'' have been reported [48].…”
In the current review of the journal Structural Chemistry, the content of the first three issues for the calendar year 2011 is related to thermochemistry. Each paper is summarized and followed by a short thermochemical comment.
“…The most stable dialkylcarbene found was a OH-NO 2 substituted derivative demonstrating increased singlet stabilization of 158.2 kJ mol -1 . Is there any stabilization seen for the corresponding dispiroalkanes?-spectroscopic evidence for slight aromatic stabilization in pentacyclopropylcyclopentane (alternatively called [5]-rotane) has been suggested [47]. We note now that the enthalpy of formation of the related species [3]-and [4]-rotane, as well as some other ''triangulanes'' have been reported [48].…”
In the current review of the journal Structural Chemistry, the content of the first three issues for the calendar year 2011 is related to thermochemistry. Each paper is summarized and followed by a short thermochemical comment.
“…It was prepared in two steps in 30% overall yield (Scheme ) starting from the diester 358 (prepared analogously to 332 , see Scheme ). The diene 360 was fully cyclopropanated to yield 1,1‘ ‘‘-dimethylquatercyclopropane 52 …”
“…The ratio of 729 to 469 depends on the reaction conditions employed. Several rationalizations of this surprisingly efficient [2 + 2] cycloaddition, which according to orbital symmetry conservation rules should not be a concerted reaction, have been published over the years. ,479a, 127 …”
Section: 4 Oligospirocyclopropanated Carbo- and
Heterocyclesmentioning
confidence: 99%
“…The diene 360 was fully cyclopropanated to yield 1,1′′′-dimethylquatercyclopropane. 260 It also proved to be possible to obtain 360 by a Wurtztype coupling of the Grignard reagent 365, which in turn was obtained from 1-bromocyclopropyl methyl ketone (363) after Wittig alkenation with triphenylmethylenephosphorane to give 364. 261 It was not possible to directly brominate cyclopropyl methyl ketone to prepare 363; instead a baseinduced cyclization of 1,3-dibromopropyl methyl ketone (362) was applied (Scheme 53).…”
“…Diese Vorstellung wird in der Tat durch Dichtefunktionaltheorie(DFT)-Rechnungen auf dem B3LYP/6-31G(d)-Niveau gestützt. Da die einzigen bekannten 1,1'-verknüpften Oligocyclopropane 4 -das 1,1-Dicyclopropylcyclopropan 4 a (n = 3, R 1 = R 2 = H), [10] seine Derivate 4 b-d (n = 3, R 1 = R 2 = OH, [11] OSiMe 3 , [12] -strukturell nicht näher charakterisiert wurden, beschlossen wir, solche [1,1';1',1'';…;1 nÀ2 ,1 nÀ1 ]Oligocyclopropane mit polaren Gruppen zu synthetisieren, um ihre Struktureigenschaften untersuchen zu können.…”
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