Deamination and related reactions of some bicyclo-octylamines

Abstract

The bicyclo-octylamines (1-5) have been deaminated by the nitrous acid method and by the decomposition of their nitrosocarbamates in ethanol. In addition, the amines (1-4) were deaminated by the decomposition of their triazenes in acetic acid. Complete quantitative analyses of the products

[diagrams displayed] from the nitrosocarbamate decompositions were obtained using analytical capillary column g.l.c. techniques developed by Banks1. Incomplete information was obtained from the nitrous acid and triazene decompositions. The results from (1) and (2) were very different from the solvolysis products of the corresponding tosylates reported earlier by Banks1 but broadly in agreement with the results from cis- and trans-4-t-butylcyclohexylamines. The endo-amine (1) gave large amounts of elimination and hydride shift products. At the unrearranged position, internal substitution to give R-X (Scheme) occurred with predominant retention of configuration. Unrearranged external substitution product, R-Y, was mainly of inverted configuration.

The exo-amine (2) gave less elimination and [equation displayed], and hydrocarbon rearrangement. Both internal and external substitution occurred with predominant retention of configuration at the unrearranged position. There was some evidence that this amine reacted, to a small extent, through a non-chair conformer. The model proposed by Maskill and Whiting involving an ion pair separated by molecular nitrogen was used, with minor alterations, to accommodate these results. The products of deamination of amines (3) and (4) were similar but not identical and included large amounts of hydrocarbon and products derived from carbon migration. However, both amines showed a tendency to maintain their structural identity when compared with the products of solvolysis of the 3 corresponding tosylates. The results suggest initial formation of the classical carbonium ions (6) and (7) from (3) and (4) respectively followed by relaxation to a common non-classical ion (8).

[diagrams displayed]

Deamination of (5) gave a very different distribution of products from (3) and (4). Very little rearranged product was observed and most of the substitution was with retention of configuration although a small but significant amount was inverted,

Initial formation of a classical carbonium ion, with nominal structure (6), followed by relaxation to the non-classical ion (9) is proposed as a possible mechanism. The different fates [diagram displayed]

of the initially formed carbonium ions from (5) and (3) are thought to be due to the different positions of the counter-ions. The mode of decomposition of adamant-2-yl-0NN-azoxy-tosylate (10) has been investigated as a link between deamination and tosylate solvolysis which would be amenable to kinetic studies. Preliminary results suggested that the mechanism is ionic, the activated complex having carbonium ion character. Isolation of 2-adamantyl tosylate from the ethanolysis of (10) is presented as evidence for internal return of tosylate anion in solvolysis of alkyl tosylates. [diagram displayed]