Bromine Azide

Häßner, Alfred

doi:10.1002/047084289x.rb257

Cited by 4 publications

(4 citation statements)

References 17 publications

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“…The TIPS substituents in these helicenes can be replaced in one step by alkyl or acyl groups (methyl and dodecyl were the alkyls studied, and acetyl was the acyl studied) when the helicenes are combined with CsF and either alkyl iodide or acyl chloride in DMF to which, in the case of the acyl chloride, DMAP has been added …”

Section: Resultsmentioning

confidence: 99%

First Friedel−Crafts Diacylation of a Phenanthrene as the Basis for an Efficient Synthesis of Nonracemic [7]Helicenes

et al. 2000

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Reported are the first examples of Friedel-Crafts reactions used to prepare 3,6-diacylphenanthrenes. 9,10-Dimethoxyphenanthrene gives its 3,6-diacetyl derivative in good yield and in large amounts. The ketone's triisopropylsilyl enol ether when combined with 1, 4-benzoquinone forms a [7]helicenebisquinone. This bisquinone's reduction product, a bishydroquinone, when combined with methanolic HCl gives the [7]helicene whose peripheral side chains are all methoxyls but whose interior hydroxyls remain. The diastereomeric (1S)-(-)-camphanates can be separated by crystallization. Their structures, analyzed by X-ray diffraction, demonstrate that the camphanates' lactone functions point away from the ring system when the helicene has the (P) configuration and toward it when the helicene has the (M) configuration. This is because the camphanates' O=C-C-O dihedral angles are, as expected, close to 0 degrees in the former and close to 180 degrees in the latter. Other derivatives of 3,6-diacetylphenanthrene and of [7]helicenebisquinone are prepared, and the crystal structure of one of the latter is analyzed.

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Section: Resultsmentioning

confidence: 99%

First Friedel−Crafts Diacylation of a Phenanthrene as the Basis for an Efficient Synthesis of Nonracemic [7]Helicenes

et al. 2000

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“…In addition to acylation, various organic transformations such as alkylations, transesterification, silylations, Baylis−Hillman reactions, nucleophilic substitutions, derivatizations of amines, and others have been catalyzed efficiently by DMAP and have been the subject of several reviews. ,,− Chiral versions of DMAP and other nucleophilic amines have been employed as catalysts in various asymmetric transformations and are reviewed elsewhere in this issue.…”

Section: Pyridine-based Organocatalystsmentioning

confidence: 99%

Organocatalytic Ring-Opening Polymerization

Kamber¹,

Jeong²,

Waymouth³

et al. 2007

Chem. Rev.

1,355

1,010

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“…The high nucleophilicity of DMAP was first noted over 30 years ago, when it was found to be an excellent catalyst for the acylation of hindered alcohols . Subsequently, DMAP has been employed as a nucleophilic catalyst in a wide range of related transformations . The first chiral DMAP-based acyl transfer reagent was reported by Vedejs and Chen in 1996 .…”

Section: Introductionmentioning

confidence: 99%

Configurationally Stable Biaryl Analogues of 4-(Dimethylamino)pyridine: A Novel Class of Chiral Nucleophilic Catalysts

et al. 1999

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A short synthetic approach toward a novel class of chiral nucleophilic catalysts, the dissymmetry of which stems from restricted rotation about an Ar-Ar bond, has been developed. The key steps of the synthesis include preparation of a nucleophilic 1-methyl-2-pyrrolino[3,2-c]pyridine core 16 by ortho-lithiation and creation of the biaryl axes via Suzuki cross-coupling reactions. Comparative HPLC studies of racemization for configurationally labile biaryls 31, 38, and 43 containing 1-methyl-2-pyrrolino[3,2-c]pyridine, 4-(dimethylamino)pyridine, and 4-(1-pyrrolidino)pyridine cores, respectively, have demonstrated that a pyrrolidino substituent ortho to the biaryl axis is optimal for slowing Ar-Ar rotation. Biaryls containing all three cores have been shown to retain DMAP-like catalytic activity in the acylation of a hindered alcohol. Biaryls 55 and 56, which are configurationally stable at ambient temperature, have also been prepared via modification of configurationally labile derivatives. Compounds 55 and 56 in optically pure form should provide a useful starting point for studies on catalytic asymmetric acyl transfer using atropisomeric analogues of DMAP.

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Bromine Azide

Cited by 4 publications

References 17 publications

First Friedel−Crafts Diacylation of a Phenanthrene as the Basis for an Efficient Synthesis of Nonracemic [7]Helicenes

First Friedel−Crafts Diacylation of a Phenanthrene as the Basis for an Efficient Synthesis of Nonracemic [7]Helicenes

Organocatalytic Ring-Opening Polymerization

Configurationally Stable Biaryl Analogues of 4-(Dimethylamino)pyridine: A Novel Class of Chiral Nucleophilic Catalysts

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