The configuration of some decalin spiro-hydantoins and amino-acids

Abstract

Several decalin spiro-hydantoins and amino-acids have been prepared. Their configurations have been determined by deamination experiments, measurements of dissociation constants, and i.r. and n.m.r. spectra. The configurations are the opposite to those previously assigned to the alkyl amino-cyclohexane-carboxylic acids.

Stereochemistry of the Bucherer–Bergs and Strecker Reactions of 4-tert-Butylcyclohexanone

“…Thus Cremlyn and Chisholm (6) found, and we have confirmed, that the amino nitrile (mostly 14) reacts with cyanic acid in acetic acid to form a urea (15) which can then by cyclized to the P-hydantoin 3 (X = Y = 0 ) . A possible reaction sequence is given in Scheme 3, although variations of this sequence can be envisaged.…”

“…On the basis of various physical and chemical properties, Munday (I) assigned the structure 2 (X = Y = 0 ) to the a-hydantoin and 3 (X = Y = 0 ) to the P-hydantoin. On the basis of other properties, Cremlyn and Chisholm (6) reversed this assignment. More recently, Maki and Masugi (7) obtained two isomeric Cbenzoyloxycyclohexane-1-spiro-5'-hydantoins (2 and 3; X = Y = 0 ; PhCOO in place of tert-Bu) from 4-benzoyloxycyclohexanone (1; PhCOO in place of tert-Bu) by the Bucherer-Bergs reaction, and established by unequivocal chemical evidence that the minor (p) isomer had the structure 3 (X = Y = 0 ; PhCOO in place of tert-Bu).…”

“…The fact that the a-hydantoin is formed in preference to the P-hydantoin indicates that the former route involves a lower overall energy barrier in going from reactants to the rate-determining step than does the latter. It seems likely that the ratedetermining step on the path to 3 (X = Y = 0 ) ticular, it can be expected that one of the two possible epimeric amino acids may be accessible by a modified Bucherer reaction when it is not SCHEME s accessible by a Strecker reaction (6). We hope to explore some of these possibilities in future work.…”

Some Stereochemical Aspects of the Strecker Synthesis and the Bucherer - Bergs Reaction

“…Atoms are shown as 30% probability ellipsoids [34] This hydrogen bonding in hydantoin (15) is also evident in the IR spectrum which exhibits vibrations consistent with the literature at 3300 cm -1 and 3200 cm -1 (N-H stretches), 1770 cm -1 and 1725 cm -1 (carbonyls, hydantoin ring), 1690 cm -1 (carbonyl acid). [21][22][23][24] The shift to lower frequency in the acid carbonyl is indicative of some intramolecular or intermolecular hydrogen bonding. This is also supported by the absence of broadness in the 3000 -2600 cm -1 region of the spectrum.…”

The Bucherer–Bergs Multicomponent Synthesis of Hydantoins—Excellence in Simplicity

“…Although Cremlyn and Chisholm [ 80 ] reversed this assignment, it was later established [ 81 ] by unequivocal chemical evidence that the major isomer of two isomeric 4-benzoyloxycyclohexane-1-spiro-5′-hydantoins ( 16 and 17 ) ( Scheme 5 ) obtained by the Bucherer–Bergs reaction from 4-benzoyloxycyclohexanone ( 15 ) had the structure of 16 (designated α) thus supporting, by analogy, Munday’s assignment. More direct evidence for this assignment came from 13 C-NMR and UV spectra as well as from acetylation of α- and β-hydantoins 13 and 14 [ 82 ].…”