20127-68-8Relevant academic research and scientific papers
Laser flash photolysis study of arylcyclopropylcarbenium ions: Cation stabilizing abilities of cyclopropyl and phenyl groups
Kirmse, Wolfgang,Krzossa, Birgit,Steenken, Steen
, p. 7473 - 7477 (2007/10/03)
Arylcyclopropylcarbenium ions, Ar(c-Pr)CH+, were generated as transient intermediates by laser flash photolysis (LFP) of trans-2,3-diphenylaziridinimines of aryl cyclopropyl ketones in 2,2,2-trifluoroethanol (TFE). The carbocations are thought to arise by way of diazo compounds and carbenes. Rate constants for the unimolecular decay in TFE and for the bimolecular reaction with methanol in TFE were obtained for Ar(c-Pr)CH+ and for analogous arylphenylcarbenium ions, ArPhCH+. Within these series, the cation stabilizing abilities of cyclopropyl and phenyl groups are found to be similar in magnitude. However, cyclopropyl responds more strongly than phenyl to increasing electron demand. Hence cyclopropyl is superior to phenyl in cation stabilizing ability for Ar = Ph but inferior to phenyl for Ar = 4-MeOC6H4.
Facile Synthesis of Stable Analogues of 2-Oxocyclobutanecarboxylates: 2-cyclobutanecarboxylates, Derivatives, and Reactions
Wessjohann, Ludger,Giller, Karsten,Zuck, Bernd,Skattebol, Lars,Meijere, Armin de
, p. 6442 - 6450 (2007/10/02)
An efficient two-step synthesis of 2-cyclobutenecarboxylate (4a) and some analogous derivatives from 2-chloro-2-cyclopropylideneacetates 2, 17, 22, and 25 and nonenolizable ketimines, especially diphenylmethyleneamine (DPMA-H), is described.A likely mechanism for the formation of 4a from the primary Michael adduct 3 of DPMA-H to 2 and its substuituted analogues is presented.The unique neighbouring group effect of the DPMA moiety to allow formation of an azaspiropentane intermediate and its regioselective rearrangement to cyclobutenaminederivatives is discussed and further exemplified by an extremely facile SET α-chlorination.Compound 4a and derivatives undergo a thermal ring-opening reaction to the corresponding butadienes with subsequent formation of 1,3-disubstituted 3,4-dihydroisoquinolines 39.Further transformations of 4a and some derivatives include transesterification, hydrolysis to methyl 2-oxocyclobutanecarboxylates, and addition of N-phenyltriazolinedione.
