1.5- deuterium shifts

Two possible pathways were envisioned for the reaction (a) cyclopropane to propylene-like rearrangement followed by 1,5-hydrogen shifts, that can equilibrate C4 and C6 as well as C3 and Cl with a slower 1,5-deuterium shift (due to the primary isotope effect) and (b) the second pathway would involve a retro-electrocyclization to a cycloheptatriene destroying the aromatic it system in the process, and this undergoes a 1,5-deuterium shift to the 1,2-benzocycloheptatriene which subsequently undergoes a 1,5-hydrogen shift to equilibrate C4 and C6 but also must equilibrate C3 with Cl. Further, a 1,5-deuterium shift in the 7-deuterio material gives the isomer from path (a) (Scheme 12.8). 

Sol 5. Upon heating, the diene I undergoes suprafacial [1,5] hydrogen shift to give the diene II, a suprafacial [1,5] deuterium shift then converts II into III and another suprafacial [1,5] deuterium shift converts it into IV. It should be noted that the major components at equilibrium are the dienes II and IV with trisubstituted double bonds. Neither of the other possible isomers is present in the equilibrium mixture, showing that no [1,5] antarafacial shifts had occurred. 

Racetnization of (15)-(-)-cxo-2,4-Dideuteroapopinene over Pd Evidence for an Intramolecular 1,3-Deuterium Shift... 

The best fit is obtained by a search, which iterates through a sequence of trials to minimize the error between the calculated overall deuterium shift, AD, and the experimentally measured shift by varying the unknown parameters (/ , Do, AD ). The average data (at least two runs) are used for the curve fitting to give mean values for the unknown parameters (yS , AD , Do). The macroscopic JC values are calculated from yS values. Finally, a resampling statistical analysis is used to evaluate the precision for each parameter in the search. 

Scheme 6.20. This ruthenium catalyst (10 mol%) was active for the cydization of ds-1 -ethynyl-2-vinyloxiranes to afford various 2,6-disubstituted phenols in reasonable yields. Under similar conditions, 1,1,2,2,-tetrasubstituted oxiranes gave the 2,3,6-trisubstituted phenols with a skeleton reorganization [22]. The 1,2-deuterium shift of the alkynyl deuterium of d-Sle was indicative of mthenium vinylidene intermediates (Scheme 6.20).

Buckingham theory and, 330 chain decomposition, 325 cooperative behavior of defects, 338 deuterium shifts, 361 dispersive interactions, 330 elastic strain, 333 electrostatic coupling, 352 exchange of positions, 351 heteroisotopic pairs, 348... 

Interpretation of 2 D NM R data obtained for cortistatin B (11) showed that it had the same skeleton as 10, but contained a hydroxyl group on C-16 with the (3 configuration. The carbon chemical shift value of 8 214.4 and the IR absorption at 1740 cm indicated the existence ofa ketone at C-16 in cortistatin C (12). Cortistatin D (13) was found to be a 17-hydroxy analog of cortistatin C, which was confirmed by "C NMR deuterium shift experiments as well as HMBC data. Analysis of NOESY data for 13 revealed the orientation of hydroxyl group at C-17 as a [13]. 

An elegant test for these two reaction pathways is the deuterium shift in the reaction... 

The matrix codeposition of CsF with HF (31,32) in an excess of argon, up to Ar/HF ratios of 3000, yielded intense bands at 1364 and 1218 cm, within a few wavenumbers of the HF2 band positions in ionic lattices 29]. The deuterium shift, upon formation of DF2, was slightly above the harmonic value of 1.41, indicating that the anion maintained a center of symmetry. Similar results were obtained with other alkali fluoride salts, but the product yield decreased as the radius of the alkali metal cation decreased. These results provided immediate confirmation of the salt/molecule technique, demonstrating that for a known system ion pair formation occurred and that the spectrum of the product anion resembled closely that of the anion in known environments. 

As in the Wacker reaction, the 1,2-oxypalladation adduct then decomposes by a deuterium shift. 

This ion can also be formed via processes involving hydrogen (or deuterium) shifts. 

Recently, we also observed abnormal deuterium distribution of a sample of benzaldehyde, which deviated significantly from the expected cluster formed by benzaldehydes produced from cinnamic aldehyde. Adulteration and use of a starting material from an unknown source were ruled out. Experiment results indicated that the deuterium shift was not due to oxidation and isotope exchange. No chromatography process was used. Our attention focused on tlie distillation process. 

The 5.1.0 product was not characterized since it gave homo 1,5- and 1,7-hydrogen shifted products under the reaction conditions, and these revealed a product distribution from the 5 yfx-7-trideuteriomethyl starting material in which 80% of the hydrogen shifted material was, in fact, the result of a deuterium shift. 

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