Asymmetric Synthesis Of Isoquinoline Alkaloids Research Articles

Asymmetric Synthesis of Isoquinoline Alkaloids: 2004-2015.

In the past decade, the asymmetric synthesis of chiral nonracemic isoquinoline alkaloids, a family of natural products showing a wide range of structural diversity and biological and pharmaceutical activity, has been based either on continuation or improvement of known traditional methods or on new, recently developed, strategies. Both diastereoselective and enantioselective catalytic methods have been applied. This review describes the stereochemically modified traditional syntheses (the Pictet-Spengler, the Bischler-Napieralski, and the Pomeranz-Fritsch-Bobbitt) along with strategies based on closing of the nitrogen-containing ring B of the isoquinoline core by the formation of bonds between C1-N2, N2-C3, C1-N2/N2-C3, and C1-N2/C4-C4a atoms. Methods involving introduction of substituents at the C1 carbon of isoquinoline core along with syntheses applying various biocatalytic techniques have also been reviewed.

ChemInform Abstract: General Asymmetric Synthesis of Isoquinoline Alkaloids. Enantioselective Hydrogenation of Enamides Catalyzed by BINAP- Ruthenium(II) Complexes.

In the presence of a small amount of RuX 2 [(R)- or (S)-BINAP] (X=anionic ligand) a wide range of (Z)-2-acyl-1-benzylidene-1,2,3,4-tetrahydro- isoquinolines are hydrogenated to give the saturated products in nearly quantitative yields and in high (up to 100%) optical yields. The enamide substrates are selectively prepared by N-acylation of the corresponding 1-benzylated 3,4-dihydroisoquinolines under suitable acylation condi- tions; some crystalline materials having low solubility are obtained by a second-order Z/E stereomutation technique utilizing the double-bond photolability and lattice energy effects. This asymmetric hydrogenation sets the key stereogenic center in predictable manner, either R or S flexibly, at the C(1) position of the benzylated tetrahydroisoquinoli- nes. The chiral products are converted by standard functional group modification to tetrahydropapaverine, laudanosine, etc. This enantio- selective hydrogenation is applied to the synthesis of morphine and its artificial analogues such as morphinans and benzomorphans of either chirality. A mnemonic device is presented for predicting the reactivity and enantiofacial selection of the BINAP-Ru catalyzed hydrogenation. Reaction with BINAP-Rh catalyst proceeds with a lower enantioselectivity and an opposite sense of asymmetric induction

Asymmetric Synthesis of Isoquinoline Alkaloids

AbstractFor Abstract see ChemInform Abstract in Full Text.

Asymmetric synthesis of isoquinoline alkaloids.

Asymmetric synthesis of isoquinoline alkaloids.

Recent Approaches to the Asymmetric Synthesis of Isoquinoline Alkaloids.

Recent Approaches to the Asymmetric Synthesis of Isoquinoline Alkaloids.

General asymmetric synthesis of isoquinoline alkaloids. Enantioselective hydrogenation of enamides catalyzed by BINAP-ruthenium(II) complexes

In the presence of a small amount of RuX 2 [(R)- or (S)-BINAP] (X=anionic ligand) a wide range of (Z)-2-acyl-1-benzylidene-1,2,3,4-tetrahydro- isoquinolines are hydrogenated to give the saturated products in nearly quantitative yields and in high (up to 100%) optical yields. The enamide substrates are selectively prepared by N-acylation of the corresponding 1-benzylated 3,4-dihydroisoquinolines under suitable acylation condi- tions; some crystalline materials having low solubility are obtained by a second-order Z/E stereomutation technique utilizing the double-bond photolability and lattice energy effects. This asymmetric hydrogenation sets the key stereogenic center in predictable manner, either R or S flexibly, at the C(1) position of the benzylated tetrahydroisoquinoli- nes. The chiral products are converted by standard functional group modification to tetrahydropapaverine, laudanosine, etc. This enantio- selective hydrogenation is applied to the synthesis of morphine and its artificial analogues such as morphinans and benzomorphans of either chirality. A mnemonic device is presented for predicting the reactivity and enantiofacial selection of the BINAP-Ru catalyzed hydrogenation. Reaction with BINAP-Rh catalyst proceeds with a lower enantioselectivity and an opposite sense of asymmetric induction

ChemInform Abstract: Asymmetric Synthesis of Isoquinoline Alkaloids.

AbstractReaction of the isoquinoline (I) with the formamidine (II) yields the chiral auxiliary (III).

Enantioselective synthesis of isoquinoline alkaloids: phenylethylisoquinoline and aporphine alkaloids

A new and improved procedure for the preparation of (R)-2-alkoxycarbonyl-1-formyl-1,2,3,4-tetrahydro-6,7-dimethoxyisoquinolines has been developed beginning from D-(−)-tartaric acid. The utility of these aldehydes in the asymmetric synthesis of isoquinoline alkaloids of high enantiomeric purity has been extended to the synthesis of phenylethylisoquinolines, which have been further transformed in straightforward steps into the homoprotoberberine and homoaporphine ring systems. In this manner, (S)-homolaudanosine, (S)-5′-methoxyhomolaudanosine, (S)-2,3,9,10,11-pentamethoxyhomoprotoberberine, and (S)-O-methylkreysigine have been synthesized. The conversion of (S)-laudanosine to (S)-glaucine, an aporphine alkaloid, has also been realized.

ChemInform Abstract: Asymmetric Synthesis of Isoquinoline Alkaloids by Homogeneous Catalysis.

AbstractEfficient asym.

Asymmetric synthesis of isoquinoline alkaloids

The use of chiral formamidines affixed to variously substituted tetrahydroisoquinolines, allows asymmetric C-C bond forming reactions to occur α- to the amino group. In this manner, a wide variety of (S)-1-alkyl-1,2,3,4-tetrahydroisoquinolines were constructed in > 90% enantiomeric excess. Choosing the proper substituents and skeletal features, an efficient entry into the benzylisoquinoline, tetrahydroprotoberberine, aporphine, and isopavine class of alkaloids was achieved.

Asymmetric synthesis of isoquinoline alkaloids by homogeneous catalysis

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAsymmetric synthesis of isoquinoline alkaloids by homogeneous catalysisRyoji. Noyori, Masako. Ohta, Yi. Hsiao, Masato. Kitamura, Tetsuo. Ohta, and Hidemasa. TakayaCite this: J. Am. Chem. Soc. 1986, 108, 22, 7117–7119Publication Date (Print):October 1, 1986Publication History Published online1 May 2002Published inissue 1 October 1986https://doi.org/10.1021/ja00282a054RIGHTS & PERMISSIONSArticle Views3395Altmetric-Citations237LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (409 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Asymmetric Synthesis of Isoquinoline Alkaloids: (R)‐ and (S)‐2‐Ethoxycarbonyl‐1‐Formyl‐6, 7‐Dimethoxy‐1,2,3,4‐Tetrahydroisoquinoline as Versatile Precursors

AbstractA method is described for the preparation of (R)‐ and (S)‐2‐ethoxycarbonyl‐1‐formyl‐6,7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline involving a Swerntype oxidation of (R)‐ and (S)‐2‐ethoxycarbonyl‐1‐hydroxymethyl‐6, 7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline {(R)‐ and (S)‐2‐(ethoxycarbonyl)calycotomine}. The utility of these aldehydes in asymmetric synthesis of isoquinoline alkaloids has been demonstrated by their conversion into (S)‐ and (R)‐xylopinine, respectively; also, the (R)‐aldehyde has been employed for the synthesis of (8S,14S)‐coralydine.