Page 425 - Advanced Organic Chemistry Part A - Structure and Mechanisms, 5th ed (2007) - Carey _ Sundberg

406 Table 4.1. Stereochemistry of Deamination in Acetic Acid

CHAPTER 4 Amine Stereochemistry
Nucleophilic Substitution
1 a CH CH CH CHDNH 2 69% inv
3
2
2
2 b CH 3 CHCH CH 3 28% inv
2
NH 2
3 c PhCH CH CHCH 3 65% ret
2
2
NH 2
2
6 5
4 d C H CHCH CH 3 10% ret
NH 2
CH 3
5 e C H CCH CH 3 24% ret
2
6 5
NH 2
a. D Brosch and W. Kirmse, J. Org. Chem., 56, 908 (1991).
b. K Banert, M. Bunse, T. Engberts, K.-R. Gassen, A. W. Kurminto, and W. Kirmse, Recl.
Trav. Chim. Pas-Bas, 105, 272 (1986).
c. N. Ileby, M. Kuzma, L. R. Heggvik, K. Sorbye, and A. Fiksdahl, Tetrahedron: Asymmetry,
8, 2193 (1997).
d. R. Huisgen and C. Ruchardt, Justus Liebigs Ann. Chem., 601, 21 (1956).
e. E. H. White and J. E. Stuber, J. Am. Chem. Soc., 85, 2168 (1963).

retention when the reaction was done in acetic acid 22 (Entry 3). However, the acetate
esters formed in these reactions is largely racemic. Small net retention was seen
in the deamination of 1-phenylpropylamine (Entry 4). The tertiary benzylic amine,
2-phenyl-2-butylamine, reacts with 24% net retention (Entry 5). These results indicate
that the composition of the product is determined by collapse of the solvent shell.
23
Considerable solvent dependence has been observed in deamination reactions. Water
favors formation of a carbocation with extensive racemization, whereas less polar
solvents, including acetic acid, lead to more extensive inversion as the result of solvent
participation.
An analysis of the stereochemistry of deamination has also been done using
4-t-butylcyclohexylamines and the conformationally rigid 2-decalylamines. The results
are summarized in Table 4.2.
NH 2
NH 2
trans,cis trans,trans

In solvent systems containing low concentrations of water in acetic acid, dioxane,
or sulfolane, the alcohol is formed by capture of water with net retention of config-
uration. This result has been explained as involving a solvent-separated ion pair that

22 N. Ileby, M. Kuzma, L. R. Heggvik, K. Sorbye, and A. Fiksdahl, Tetrahedron: Asymmetry, 8, 2193
(1997).
23
W. Kirmse and R. Siegfried, J. Am. Chem. Soc., 105, 950 (1983); K. Banert, M. Bunse, T. Engbert,
K.-R. Gassen, A. W. Kurinanto, and W. Kirmse, Recl. Trav. Chim. Pays-Bas, 105, 272 (1986).