Bestimmung des Chiralitätssinns der enantiomeren 2,6-Adamantandiole

Determination of the Chirality Sense of the Enantiomeric 2,6-Adamantanediols The enantiomers of 2,6-adamantanediol ( 1 ) are resolved via the diastereoisomeric camphanoates. The (2R,6R)-chirality sense for (?)- 1 and (2S,6S) for (+)- 1 was determined by chemical correlation with (?)-(1R,5R)-bicyclo[3.3.1]nonan-2,6-dion ((1R,5R)- 3 ) of known absolute configuration in the following way: alkylation of the bis(pyrrolidine enamine) of (?)-(1R,5R)- 3 with CD₂I₂ and hydrolysis of the product gives the enantiomer 4 of (4,4-D₂)-2,6-adamantanedione. Reduction of 4 with LiAlH₄ leads to one enantiomer (Scheme 2) of each of the three diols 5 – 7 of known absolute configuration. The three diols are themselves configurational isomers due to the presence of the CD₂ group, but correspond otherwise entirely to the enantiomeric diols 1 . Accordingly, they can also be separated by means of their diastereoisomeric camphanoates to give the diols 5 / 6 and 7 . These samples are easily distinguished and identified by their characteristic ¹H-NMR spectra (cf. Fig. 2). This allows to identify the (2R,6R)- and (2S,6S)-enantiomer of 1 on the basis of their behavior in the resolution experiment analogous to that of the diols 5 / 6 and 7 , respectively. The diol (?)- 1 must have the (2R,6R)-configuration because it forms, like the diols 5 / 6 , with (?)-camphanic acid the diastereoisomeric ester less soluble in benzene. The diol (+)- 1 has (2S,6S)-configuration, because it forms, like 7 , with (+)-camphanic acid the diastereoisomeric ester less soluble in benzene. The bis(4-methoxybenzoate) of (?)-(2R,6R)- 1 shows chiroptical properties which are in accordance with Nakanishi's rule for two chromophores having coupled electric dipol transition moments arranged with a left-handed torsion angle.     

2,6-di-tert-butyl-4-perimidylphenols and their oxidation

1,8-Naphthylenediamine was reacted with 2,6-di-tert-butyl-4-formyl-phenol to produce 2,6-di-tert-butyl-4-(1,3-dihydro-perimidyl) phenol (I). The latter was coverted into 2,6-di-tert-butyl-4-(1H-perimidyl)phenol (II) by oxidizing I with sodium pyrosulfate. When phenol II was oxidized by lead dioxide in toluene and THF, the EPR spectra revealed a 12-component multiplet with perimidyl splitting constants a¹ _N=a³ _N=a_H ^NH=0.2 mT; a_H ^6.7=0.6 mT.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 1, pp. 64–67, January, 1992.     

1-(2,6-二甲苯基)-1-苯乙酰基-4-丁基氨基脲的合成与表征

１－（２，６－二甲苯基）－１－苯乙酰基－４－丁基氨基脲的合成与表征刘长令李宗成张少铭龚葆青（化工部沈阳化工研究院１１００２１）杀菌剂甲霜灵和酰胺分别由瑞士汽巴－嘉基公司及山道士公司于７０年代后期开发的、主要应用于防治藻菌纲病原菌特别是卵菌亚纲病原菌...     

Zur Kenntnis der Reaktionsfähigkeit von 4-Hydrazino-2,5-di-tert.-butyl-2-methyl-2H-imidazol

4-Hydrazino-2.5-di-tert.-Butyl-2-methyl-2H-imidazole (1) reacts with aldehydes and ketones to give condensation products (2 a-1). The reaction of1 with acyl chlorides and dicarboxylic acid chlorides gives rise to the corresponding 4-acylhydrazino-2H-imidazoles (3 a, b) and dicarboxylic-bis(imidazole-4-yl)-hydrazides (4 a-c) resp. Heating1 with acetyl bromide, ethyl orthoformate and 3-bromo-4-methyl-2-pentanone affords new condensedring systems5 a, b and7, resp.     

Zur Stereoisomerie der 2,6-Dichlor-4-methoxyheptane

2,6-Dichloro-4-methoxy-heptanes may exist as 2 optical active isomers and 2 meso compounds. By double addition of ,-dichloro-dimethylether to propene a mixture of these stereoisomers was obtained. They were separated by HPLC. Using¹H- and¹³C-NMR-spectroscopy their configuration could be established.

     

4-取代-2,6-二(羟甲基)苯酚的选择氧化

酚类由于本身容易氧化,仅在非常温和的条件下才能直接使4-取代-2,6-二(羟甲基)苯酚中的羟甲基氧化成醛基。文献报道了用活性二氧化锰可以将2,6-二(羟甲基)-4-甲基苯酚氧化成2-羟基-5-甲基-1,3-苯二甲醛,但要使两个羟甲基中只有一个被氧化却是困难的。文献报道了由芳氧基溴化镁与甲醛作用制备水杨醛类化合物的方法,并认为中间产物是邻羟甲基苯酚的镁盐,后者与甲醛之间通过负氢离子转移的分子间氧化还原反应生成相应     

Einfluß der Ldsungs mittel auf die Geschwindigkeit der oxydativen Polykondensation des 2,6-Dimethylphenols

Ohne Zusammenfassung     

Polyoxyphenylen. 4. Mitt.: Einflu? der Bedingungen der 2,6-Xylenolpolymerisation auf den Stickstoffgehalt im Polymer

Ohne Zusammenfassung     

Einflu? der Ldsungs mittel auf die Geschwindigkeit der oxydativen Polykondensation des 2,6-Dimethylphenols

Ohne Zusammenfassung     

Polyoxyphenylen. 4. Mitt.: Einfluß der Bedingungen der 2,6-Xylenolpolymerisation auf den Stickstoffgehalt im Polymer

Ohne Zusammenfassung     

Nachweis des Octadecyl-3-(3,5-di-tert. butyl-4-hydroxyphenyl)-propions?ureesters im Kalbs-Thymus durch GC/MS

Ohne Zusammenfassung

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Spectrophotometric determination of diamidophenylphosphate in fertilizers in the presence of additives

     

2,6-Pyridinedimethanol from 2,6-lutidine. A comparison of chlorination and oxidation routes

Chlorination of lutidine to 2,6-bis(chloromethyl)pyridine, or its catalytic oxidation to 2,6-pyridinedicarboxaldehyde, respectively, followed by hydrolysis or by hydrogenation to the end product, were investigated as possible routes for the title process. In both cases interesting overall yields were obtained. The choice between the routes seems then to depend more on economical, rather than on chemical considerations.

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2,6- () 2,6- , . . , , , .

     

Synthesen der Phosphono- bzw. Phosphino-Analoga des Pantothensäure-ethylesters und des Phosphono-Analogons des Pantetheins

Syntheses of Phosphonic- and Phosphinic Analogues of Pantothenic Acid Ethyl Ester and of the Phosphonic Analogue of Pantetheine The replacement of amino acids in peptides by phosphono-analogous (aminoalkyl)phosphonic acids 1 , (2-aminoethyl)phosphonic acid ( 2 ) and substituted derivatives has been an important aspect of peptides research in the last years. In pantothenic acid ( 3 ), there is a peptide linkage between (2R)-2,4-dihydroxy-3,3-dimethylbutyric acid and the amino group of β-alanine, and in pantetheine ( 4 ), there is a second peptide linkage between the β-alanine and cysteamine. The synthesis of phosphono and phosphino analogues of pantothenic acid ethyl ester, where the β-alanine is replaced by the diethyl ester of (2-aminoethyl)phosphonic acid and the ethyl ester of (2-aminoethyl)methylphosphonic acid, respectively, and the syntheses of the phosphono analogue of pantetheine, where the β-alanine is replaced by (2-aminoethyl)phosphonic acid, are described.     

New Stereoselective Synthesis of 4-Butyl-α-agarofuran

A potent anxiolytic 4-butyl-α-agarofuran (AF-5) was synthesized from ( )dihydrocarvone. Acid catalyzed hydration of ( )dihydrocarvone and interconversion with β-O-ketone 8 and the key intermediate α,β-unsaturated ketone 5 made this synthesis more practical.