Chemistry of methylnorbornyl cations. IV. Ratios of rates of nucleophilic capture of the cations at Wagner-Meerwein-related sites

Abstract

2573ketone. This mixture was carried through to the hydrocarbon as separated by preparative vpc on column G-1 at 130°, shown by before. The pyrolysis product in this case, despite scrupulous infrared to be identical with material obtained from previous vacuum drying of the sodium salt, was contaminated with about preparations, and its purity checked by capillary vpc. It had 30% of tetrahydrofuran. The other products consisted of about [ C Y ]~~.~D -16.4" (95x ethanol), a value essentially identical in 6 % 3-endo-methyl-2-norbornanone (12), 1.5 % 2-methyl-2-nor-magnitude and opposite in sign with that of hydrocarbon obtained bornene, 1.5 % of an unidentified compound, and the remainder above in Scheme I directly from 7-anti-methyl-2-exo-norbornyl 3-methylnortricyclene. The tricyclic hydrocarbon was again acetate (2b).Abstract: A detailed study of the product distributions from solvolyses and deaminations of a number of precursors of methylnorbornyl cations permits the evaluation of the relative rates of capture of these species at each of the two Wagner-Meenvein-related sites. A direct steric effect on nucleophilic approach and another effect which opposes developing hydrogen-methyl repulsions in the transition state are noted. The characteristic capture ratios observed in the solvolytically produced ions apply also to the deaminatively produced ones, the major difference between the two processes being the excess of "direct substitution" observed in deamination. A comparison of the deamination results with those obtained earlier in the unsubstituted norbornyl case reveals that the "direct substitution" is very sensitive to a /3-methyl steric effect, which causes a complete reversal of the stereochemistry of the process.he summarizing rearrangement scheme given in T paper I 3 of this series outlines the interconversions of a set of "core" methylnorbornyl cations A, B, and C by 6,2-hydride shifts (Chart I) a n d their escape to Chart I. "Core" System "periphery" cations AI, BI (=B2), and C1 by 3,2-hydride shifts. T h e present paper provides evidence for this scheme from studies of the products derived from solvolyses of various methylnorbornyl derivatives. 1 1 B I I 5 6 -A 2 1 3 4 a, X = OPhth; b, X = O E H ; c, X = OAc; d, X = OH; e, X = OBs; f, X = NHI (1) (a)

Oxidative decarboxylation of the 3-methyl-2-carboxynorbornanes with lead tetraacetate

“…workers (7). The formation of significant amounts of acetates with rearranged skeletons supports the premise of cationic interniediates since a methylnorbor~iyl radical would not be expected to rearrange by analogy with the bornyl radical which is not subject to skeletal change at these teniperatures (8).…”

Bromohydrin formation in dimethyl sulfoxide. V. Reaction of norbornene

“…sg/ro-7-BromobÍcyclo[2.2.1]heptan-2-e:¡;ool (3) 21.7 ezo-si/M-2,7-Dibromobicyclo[2.2.1 Jheptane (11) 8.3 <rofo'-7-Bromobicyclo[2.2.1]heptan-2-e;ro-ol (8) 4.4 syn-7-Bromobicyclo[2.2.1]heptan-2-one (7) 2.2 endo-exo-2,3-Dibromobicyclo [2.2.1] heptene (10) 1.6…”

Cycloaddition of the acridizinium ion with norbornene derivatives

“…sg/ro-7-BromobÍcyclo[2.2.1]heptan-2-e:¡;ool (3) 21.7 ezo-si/M-2,7-Dibromobicyclo[2.2.1 Jheptane (11) 8.3 <rofo'-7-Bromobicyclo[2.2.1]heptan-2-e;ro-ol (8) 4.4 syn-7-Bromobicyclo[2.2.1]heptan-2-one (7) 2.2 endo-exo-2,3-Dibromobicyclo [2.2.1] heptene (10) 1.6…”

“…Anal. Caled for C22H1SBF4N03: C, 61.28; , 4.21; N, 6,6a,7,10,10a, ll-Hexahydro-6, ll-o-benzeno-7,10-methanoacrldizinium Fluoroborate (10 and 11).-In refluxing acetonitrile 1 reacted with excess norbornadiene in 24 hr to afford a 90% yield of a mixture of syn (10) and anti (11) isomers, mp ca. 280°.…”

“…The reaction was carried out stepwise, the first addition taking place in refluxing acetonitrile and yielding a mixture consisting of approximately 73% syn (10) and 27% anti (11) isomers. Fractional crystallization of the mixture did not result in a useful change in isomer ratio, so the final step in the synthesis was carried out using the mixture.…”