Structures of 8α‐ and 8β‐t‐Butyl‐trans‐decahydroquinoline Picrates and 8α,Nβ‐Dimethyl‐trans‐decahydroquinoline p‐Toluenesulfonate

Hargrave, Karl D.; Eliel, Ernest L.

doi:10.1002/ijch.198000060

Israel Journal of Chemistry

1980

DOI: 10.1002/ijch.198000060

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Structures of 8α‐ and 8β‐t‐Butyl‐trans‐decahydroquinoline Picrates and 8α,Nβ‐Dimethyl‐trans‐decahydroquinoline p‐Toluenesulfonate

Karl D. Hargrave

Ernest L. Eliel

Abstract: The structures of the title compounds I, II and III have been determined by X‐ray crystallography. All three compounds, including the 8β‐t‐butyl isomer II(axial t‐butyl), exist in double chair forms. Compound II is deformed by an outward tilt as well as a substantial twist (16.2°) of the t‐butyl group away from the staggered conformation. A slightly lesser twist of 13.7° is found in the equatorial t‐butyl isomer I. Outward bending of the axial N‐methyl group also occurs in compound III.

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Cited by 7 publications

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ChemInform Abstract: STRUCTURES OF 8α‐ AND 8β‐T‐BUTYL‐TRANS‐DECAHYDROQUINOLINE PICRATES AND 8α,Nβ‐DIMETHYL‐TRANS‐DECAHYDROQUINOLINE P‐TOLUENESULFONATE

Hargrave¹,

Eliel²

1980

Chemischer Informationsdienst

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The structures of the title compounds 1. 11 and III have been determined by X-ray crystallography. All three compounds. including the RI3-t-butyl isomer lI(axial r-butyl), exist in double chair forms. Compound 11 is deformed by an outward tilt as well as a substantial twist (16.2°) of the r-butyl group away from the staggered conformation. A slightly lesser twist of 13.7°is found in the equatorial I-butyl isomer 1. Outward bending of the axial Nvmethyl group also occurs in compound III. d;; / CH 3 vm VD Fig. 2.pair is largely axial) does so to a much lesser extent. It was deduced that the lone pair in IV as in VI is predominantly axial. Hence the NH is equatorial.These studies followed earlier ones' involving Nmethyl homologs (VII), (IVm) and (VIII) in which 13C NMR spectroscopy was used as a tool and which demonstrated that the N-Me group in IVm is almost exclusively equatorial.An interesting difference between the N-Me and N-H compounds is that in the former, but not in the latter, an axial lone pair leads to a sizeable upfield NMR shift of the antiperiplanar proton on the adjacent carbon (C-2). The absence of such a shift invalidates earlier arguments" in support of predominantly axial NH in piperidine.Basic to our studies was the assumption that the 813 -isomer VI in fact exists in the double chair conformation which must then have an axial r-butyl. While preliminary evidence in this regard was obtained from 13C NMR spectroscopy: it seemed advisable to establish the point unequivocally by X-ray crystallography. Whereas the amine VI was a liquid at room temperature, the picrate II was crystalline and suitable for structure study. It proved to be in the double chair form with axial r-butyl, If the (more congested) salt II is in the double chair form, it may be argued that the less congested free amine VI should, a fortiori, have the double chair conformation also.That compound II does not escape into the twist form is really not so surprising, since for a trans-decalin system with a bulky axial substituent at Col, both the twist-chair and twist-twist conformations are relatively rigid and involve the axial l-substituent in severe steric interactions of their own.Compound I, with equatorial r-butyl, was investigated for comparison with II; it also exists in the double chair as expected. Finally, for the sake of completeness, we investigated the structure of the N-methylamine salt III in which the N-methyl group is necessarily axial. The free lV R =H IVm R:CH 3

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ChemInform Abstract: STRUCTURES OF 8α‐ AND 8β‐T‐BUTYL‐TRANS‐DECAHYDROQUINOLINE PICRATES AND 8α,Nβ‐DIMETHYL‐TRANS‐DECAHYDROQUINOLINE P‐TOLUENESULFONATE

Hargrave¹,

Eliel²

1980

Chemischer Informationsdienst

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Azabicyclo chemistry. 7. Ultra‐high field (600 MHz) NMR spectroscopy in solving conformational problems: cis‐Octahydroindoles

Mokotoff

Hill

1988

Journal of Heterocyclic Chem

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Studies using ultra‐high field (600 MHz) nmr spectroscopy has allowed us to assign the conformational preference of cis‐octahydroindoles, including the position of their nitrogen lone‐pair electrons. Lithium aluminum hydride reduction of cis‐octahydroindol‐2‐one (4) gave cis‐octahydroindole (5a) which showed three distinct nmr resonances, the C7a proton at δ 3.04 (apparent q, J = 5.3 Hz) and the two C2 protons at δ 3.10 and 2.94. The latter two resonances were absent in the C2 deuterated compound 5b. Deuteromethylation of 5a, via a urethane intermediate, gave 1‐deuteromethyl‐cis‐octahydroindole (8a) which showed resonances at δ 3.12 for the α‐faced C2 proton, the β‐faced C2 proton at δ 2.17, and the C7a proton at δ 2.15. The resonances at δ 3.12 and 2.17 are absent in the corresponding C2 deuterated compound 8b, and the C7a remains as a doublet of triplets (d, J = 5.5 Hz; t, J = 3.8 Hz). Interpretation of the above data led us to assign 8a as the cis compound with nitrogen axial, and the lone pair electrons in a pseudo‐axial position and antiperiplanar to the C7a and β‐faced C2 protons. The amine 5a is also cis and has the nitrogen axial, but the lone pair electrons are pseudo‐equatorial. Inspection of the Bohlmann band region in the ir of 5a and 8a supports the above assignments. These investigations thus suggest, in cis‐octahydroindoles, the following steric order: methyl > lone pair > H.

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Structure of arylthioniacycloalkane salts with a hydroxy group in the benzene ring. IX. Crystal structure of P-hydroxyphenylthiophanium picrate and statistical analysis of the picrate-anion geometry

et al. 1984

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Structures of 8α‐ and 8β‐t‐Butyl‐trans‐decahydroquinoline Picrates and 8α,Nβ‐Dimethyl‐trans‐decahydroquinoline p‐Toluenesulfonate

Cited by 7 publications

References 33 publications

ChemInform Abstract: STRUCTURES OF 8α‐ AND 8β‐T‐BUTYL‐TRANS‐DECAHYDROQUINOLINE PICRATES AND 8α,Nβ‐DIMETHYL‐TRANS‐DECAHYDROQUINOLINE P‐TOLUENESULFONATE

ChemInform Abstract: STRUCTURES OF 8α‐ AND 8β‐T‐BUTYL‐TRANS‐DECAHYDROQUINOLINE PICRATES AND 8α,Nβ‐DIMETHYL‐TRANS‐DECAHYDROQUINOLINE P‐TOLUENESULFONATE

Azabicyclo chemistry. 7. Ultra‐high field (600 MHz) NMR spectroscopy in solving conformational problems: cis‐Octahydroindoles

Structure of arylthioniacycloalkane salts with a hydroxy group in the benzene ring. IX. Crystal structure of P-hydroxyphenylthiophanium picrate and statistical analysis of the picrate-anion geometry

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