Amine Oxides. X. Thermal Decomposition of the N-Oxides and Methohydroxides of cis- and trans-N,N-Dimethyl-2-aminocyclohexanol and cis- and trans-N,N-Dimethyl-2-aminocycloöctanol

Cope, Arthur C.; Ciganek, Engelbert; Lazar, Joseph

doi:10.1021/ja00872a025

Cited by 12 publications

(5 citation statements)

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“…Unter milden Bedingungen (40") entstand aber nur das N-Methyloxazin 62 (vgl. [74])16). Das gewunschte N, N-Dimethylamin 63 wurde erst unter energischeren Bedingungen gebildet.…”

unclassified

“…Normale Aufarbeitung (Ather/Wasser) und 19) Dieses Ergebnis ist im Einklang mit den Resultaten von Cope et al, die bei der Pyrolyse der Aminoxide von cis-und trans-2-Dimethylamino-cyclohexanol bzw. -cyclooctanol neben den jeweiligen Eliminierungsprodukten wechselnde Anteile der entsprechenden Dimethylaminoalkohole und N-Methyloxazolidine isolierten [74]. (3), 221 (2), 191 (12), 162 (5), 161 (52), 151 (13), 149 (24), 148 (17), 119 (ll), 107 (6), 105 (18), 97 (5), 91 (lo), 88 (6), 87 (7), 77 (5), 69 (lo), 45 (loo), 29 (5).…”

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Carbocyclische Verbindungen aus Monosacchariden. I. Umsetzungen in der glucosereihe

Bernet

Vasella

1979

Helvetica Chimica Acta

338

131

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A method for the preparation of pentasubstituted cyclopentanes from monosaccharides is presented, involving two crucial steps, viz. the reductive fragmentation of 5-bromo-5-deoxyglucosides (such as 10, 17 and 23, see Scheme 3) with Zn or butyl lithium yielding 5,6-dideoxy-hex-5-enoses (such as 11 a.nd 24, see Schemes 3 and 4 ) , and the subsequent cyclization of these hexenoses with N-methyl-or N-(alkoxyalky1)hydroxylamines (via the corresponding nitroines) to form cyclopentano-isoxazolidines (see Scheme 2). Thus, the glucosides 17 and 23 were converted diastereoselectively and in good yields into the cyclopentano-isoxazolidines 27 and 45 (Schemes 5 and 7), which were characterized by their transformation into various derivatives. 27 and 45 were correlated through the common derivative 62. The configuration of the cyclization products were established1 by pyrolysis of the N-oxide 65 to the enol ether 67 (Scheme 10).

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“…Unter milden Bedingungen (40") entstand aber nur das N-Methyloxazin 62 (vgl. [74])16). Das gewunschte N, N-Dimethylamin 63 wurde erst unter energischeren Bedingungen gebildet.…”

unclassified

Carbocyclische Verbindungen aus Monosacchariden. I. Umsetzungen in der glucosereihe

Bernet

Vasella

1979

Helvetica Chimica Acta

338

131

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“…If one con~pensates for the number of hydrogens of each type available (6:2), elimination toward a methyl01 group is about one-eighth as fast as that to~vard methyl. The correspoilding factor for secondary alcohol -methylene competition ranges from 0.1 to 0.4 (2).…”

Section: Discussionmentioning

confidence: 99%

“…The decomposition of trialkylamine oxides to olefin and dialkylhydroxyla~ui~~e (Cope reaction) is kno~vn to proceed in good yield via a cyclic intra~volecular transition state (I). The pyrolysis of some N,N-dimethyl-2-h)idrox)i-c)icloall~yla1nine oxides has been reported (2). These give allylic alcohol and ltetone (via enol), in a ratio ranging from 5 : l to 20:1, where stereoche~nical factors permit competitive elimination.…”

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confidence: 99%

Pyrolysis of Dimethylethanolamine Oxide Monohydrate

Shulman¹

1966

Can. J. Chem.

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“…Thus, heating neat 6 to 1458 for 15 min gave the enol ether 7 (63%) besides 22% of the tertiary amine 5 (cf. [19]). …”

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Conformationally Biased Mimics of Mannopyranosylamines: Inhibitors of β-Mannosidases?

Remeň

Vasella

2002

HCA

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The enol ether 7 was prepared by cleavage of the NÀO bond of the known isoxazolidine 3, followed by Nalkylation to 4, silylation and oxidation to the N-oxide 6, and Cope elimination. Cu-Catalysed cyclopropanation of 7 led to the diastereoisomeric cyclopropanes 8 and 9, which were subjected to a Curtius degradation. The resulting carbamates 12 and 16 were deprotected to the ammonium salts 14 and 18, respectively. Both salts adopt a B 1,4 conformation, similarly as the ester 8, while the isomeric ester 9 exists in a ca. 6 : 4 equilibrium of the 4 C 1 and B 1,4 conformers. The b-mannoside mimic 14 does not inhibit snail b-mannosidase at 10 mm, but the amannoside mimic 18 inhibits Jack bean a-mannosidase (IC 50 80 mm). These results are in keeping with the postulate that glycoside cleavage of b-d-glycopyranosides requires a conformational change in agreement with the principle of stereoelectronic control.Introduction. ± Cleavage of glycopyranosides by retaining b-glycosidases requires a conformational change of the tetrahydropyran ring to satisfy the principle of stereoelectronic control that postulates an antiperiplanar orientation of the scissile C,O bond and the double occupied nonbonding orbital of the endocyclic oxygen [1 ± 3]. Crystal structures of three endo-glycosidases in complex with their substrate [4] [5] or a substrate analogue [6] are in keeping with this hypothesis. Glycoside mimics possessing a skew-boat or boat-like conformation, and interacting with the catalytic acid and/or the catalytic nucleophile could, therefore, be closer to the transition state of an enzymic b-glycoside cleavage than mimics of a solvated oxycarbenium cation 1 ). In keeping with this assumption are the observations that a tetrazole, mimicking the shape of an oxycarbenium cation, is only a partial transition-state analogue [7], that aminocyclopentitols possessing a pseudo-axial amino group are strong and selective inhibitors of b-glucosidases and b-galactosidases [8] [9], and that the (racemic) mannoconfigured isoquinuclidine 1 mimicking the 1,4 B conformation of a b-mannoside is a selective inhibitor (K i 0.17 mm) of snail b-mannosidase [10]. The inhibition by 1 is due to the free amine, as it is expected if the interaction of the amino group with the catalytic acid of the mannosidase contributes to binding. However, the inhibition could also be due to the interaction of the amino group of 1 with a carboxy group that does not correspond to the catalytic acid. There are three carboxy groups in the active site of a b-mannosidase from Pyrococcus horikoshi [11]. Two correspond to the catalytic acid and nucleophile, respectively. The third one appears to be close enough to the C(2)ÀOH group to interact with it, possibly facilitating a conformational change where the axial C(2)ÀOH group moves towards an equatorial position. This carboxy group,

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Amine Oxides. X. Thermal Decomposition of the N-Oxides and Methohydroxides of cis- and trans-N,N-Dimethyl-2-aminocyclohexanol and cis- and trans-N,N-Dimethyl-2-aminocycloöctanol

Cited by 12 publications

References 1 publication

Carbocyclische Verbindungen aus Monosacchariden. I. Umsetzungen in der glucosereihe

Carbocyclische Verbindungen aus Monosacchariden. I. Umsetzungen in der glucosereihe

Pyrolysis of Dimethylethanolamine Oxide Monohydrate

Conformationally Biased Mimics of Mannopyranosylamines: Inhibitors of β-Mannosidases?

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