63049-05-8Relevant academic research and scientific papers
Competitive 1,2-C Atom Shifts in the Strained Carbene Spiro[3.3]hept-1-ylidene Explained by Distinct Ring-Puckered Conformers
Rosenberg, Murray G.,Schrievers, Theodor,Brinker, Udo H.
, p. 12388 - 12400 (2016/12/23)
Spiro[3.3]hept-1-ylidene is a markedly strained carbene reaction intermediate that was generated by high-vacuum flash pyrolysis (HVFP) of the corresponding p-tosylhydrazone sodium salt. Five hydrocarbons were produced from the Bamford-Stevens reactant in 82% overall yield. The carbene undergoes two [1,2]-sigmatropic rearrangements via competing 1,2-C atom shifts. Ring-contraction yields cyclopropylidenecyclobutane, while ring-expansion affords bicyclo[3.2.0]hept-1(5)-ene. The ring contraction is regiospecific despite the formation of some 1-methylenespiro[2.3]hexane. It does not originate from the carbene under HVFP conditions. Instead, it comes from a methylenecyclopropane-type rearrangement of chemically activated cyclopropylidenecyclobutane. Similarly, some chemically activated bicyclo[3.2.0]hept-1(5)-ene rearranges to 1,2-dimethylenecyclopentane via electrocyclic ring-opening. Accounting for the conversion of primary products to secondary ones, relative yields indicate that ring-contraction within the carbene prevails over ring-expansion by a factor of 6.7:1. Computational chemistry was used to assess the structures, conformations, energies, strain energies, transition states, and activation energies of these rearrangements with the goal of explaining product selectivities. The dual-ringed carbene is predicted to assume four distinct geometric conformations that have a bearing on transition-state selection. The reactive cyclobutylidene units of two conformers are significantly puckered, like cyclobutylidene itself, while those of the other two are flatter. The selectivity of the title carbene is compared with that of spiro[2.3]hex-4-ylidene.
The chemistry of small-ring compounds. Part 47. Small-ring interference in the ozonolysis of cyclopropylidenecycloalkanes
Heuvel, C. J. M. van den,Hofland, A.,Velzen, J. C. van,Steinberg, H.,Boer, Th. J. de
, p. 233 - 240 (2007/10/02)
Ozonolysis of olefins Ia-c containing a cyclpropylidene group, does not follow the classical Criegee mechanism but gives the anomalous products IIa-c, IIIa-c, IVa-c, and Va-c, as outlined in Scheme 2.None of these oxidation products contains the cycloprop
Cyclopropylidenecyclanes Oxydation par l'acide peroxycarboximidique
Bertrand, Marcel,Meou, Alain,Tubul, Arlette
, p. 3691 - 3694 (2007/10/02)
The title reaction gives a mixture of four compounds .A 2-cyclohexyllideneoxetane is invoked as intermediary to account for the unusual lactone formation.
Polyspiranes, 6. Attempted Direct Homologation of Trispirodecan-10-one and 10-(Benzenesulfonimido>trispirodecane with Diazocyclopropane
Fitjer, Lutz,Wehle, Detlef
, p. 1061 - 1069 (2007/10/02)
The reaction of the ketone 1, m = 0, with diazocyclopropane proceeds predominantly to the spiroalkylation product 9, m = 0, with a minor amount of the homologation product 1, m = 1.The use of the sulfonimide 23 significantly increases the yield of 1, m =
