766-25-6Relevant academic research and scientific papers
34. Norbornanes Part 20 Inductivity and Bridging in 2-Norbornyl Cations
Bielmann, Rolf,Fuso, Francesco,Grob, Cyril A.
, p. 312 - 319 (2007/10/02)
The solvolysis rates and products of several 1-substituted 2-exo- and 2-endo-norbornyl p-toluenesulfonates 7 and 8, respectively, have been determined.Hydrolyses of these epimeric tosylates yielded rearranged products in varying amounts, except when the substituent was COOCH3 or CN.The logarithms of the rate constants (log k) for the endo-series 8 correlated linearly with the corresponding inductive constants ?q1 with a reaction constant ρ1 of -1.24.On the other hand, log k values for the exo-series 7 appear to fit two regression lines,the first line (ρ1 = -1.90) defined by the tosylates that ionize, with rearrangement, to the tertiary cations 11, the second (ρ1 = -1.86) by the tosylates 7(R = H, COOCH3, and CN) that ionize to an asymetrically bridged secondary cation 19.These results confirm the unique participation of C(6) with a ρ1 of -2.00 in the ionization of 2-exo-norbornyl tosylate.
Deamination Reactions, 39. Decomposition of 1-Methylnorbornane-2-diazonium Ions
Banert, Klaus,Kirmse, Wolfgang,Wroblowsky, Heinz-Juergen
, p. 3591 - 3610 (2007/10/02)
Nitrous acid deaminations of 1-methyl-exo-2-norbornylamine (19) and of the epimeric 2-methyl-2-norbornylamines (32, 34) in water yielded endo-2-methyl-exo-2-norbornanol (42a) exclusively.In contrast, 1-methyl-endo-2-norbornylamine (23) afforded 2-methylbicycloheptan-2-ol (13a, 20percent) and 1-methyl-endo-2-norbornanol (14a, 17percent) in addition to 42a.The formation of bicycloheptyl derivatives 13 is accentuated by better nucleophiles, as shown by photolyses of 1-methyl-2-norbornanone tosylhydrazone (35) in methanol/methoxide, and in the presence of lithium azide. 14 and (in part) 13 are thought to originate from 7-bridged 1-methylnorbornyl cations (10).A substantial fraction of 13 stems from the open 2-methylbicycloheptyl cation (12).The contributions of 10 and 12 have been elucidated by means of 3-D2 labels.Introduction of an exo-3-methyl group (48, 50) enhances participation of the C-1 - C-7 bond.Cations 57 and 61 are the predominant intermediates generated from 1,exo-3-dimethylnorbornane-endo-2-diazonium ions (53).Less polar solvents (acetic acid, 2-ethylhexanoic acid) induce variations in product distribution which are attributed to increasing solvolytic displacement (ks) and ion pair collapse.
Norpinyl-Norbornyl Rearrangements: 2-Methyl- and 2,exo-6-Dimethylbicycloheptane Derivatives
Banert, Klaus,Kirmse, Wolfgang,Wroblowsky, Heinz-Juergen
, p. 2474 - 2485 (2007/10/02)
Solvolyses of 2-methylbicyclohept-2-yl-4-nitrobenzoate (9), the nitrous acid deamination of the corresponding amine (4e), and acid-catalyzed rearrangements of various 2-methylbicycloheptane derivatives (4a - c) have been investigated. 2-Methylbicycloheptyl (4) and 1-methyl-endo-2-norbornyl (10) products prevailed; minor quantities of 2-methyl-exo-2-norbornyl derivatives (12) were also obtained.The product distributions were independent of the precursor but were strongly affected by the nucleophilicity of the solvent.Our observations are consistent with the 7-bridged norbornyl cation 6 as the predominant intermediate.Further stabilization of 6 by exo-3-methyl substitution is indicated by the results of the acid-catalyzed rearrangement of 2,exo-6-dimethylbicycloheptan-2-ol (17).
