Hydroboration. 44. Diisopinocampheylborane of High Optical Purity. Asymmetric Synthesis via Hydroboration with Essentially Complete Asymmetric Induction

1976 ◽  
Vol 15 (1-2) ◽  
pp. 12-16 ◽  
Author(s):  
Herbert C. Brown ◽  
Nung Min Yoon
Keyword(s):  
Asymmetric Synthesis ◽  
Optical Purity ◽  
Asymmetric Induction ◽  
High Optical Purity

Diels–Alder addition of the fumarate and acrylate of S-methyl lactate to α-hydroxy orthoquinodimethanes

1989 ◽  
Vol 67 (4) ◽  
pp. 574-579 ◽  
Author(s):  
James L. Charlton ◽  
Guy L. Plourde ◽  
Kevin Koh ◽  
Anthony S. Secco
Keyword(s):  
Asymmetric Synthesis ◽  
Optical Purity ◽  
Diels Alder ◽  
Asymmetric Induction ◽  
Synthetic Route ◽  
Methyl Lactate ◽  
High Optical Purity ◽  
Single Diastereomer ◽  
Potential Use

The cycloaddition of α-hydroxy orthoquinodimethane, generated photochemically from 2-methylbenzaldehyde, to the fumarate and acrylate of S-methyl lactate has been found to give a single diastereomer with high asymmetric induction (>95% de). This reaction provides a new and versatile synthetic route to substituted tetralins of high optical purity. A trans stereochemistry between the vicinal hydroxyl and carboxylactyl groups has been established for these cycloadducts. This is in contrast to previous work where cis stereochemistry has always been found for major cycloadducts of α-hydroxy o-QDMs. The high asymmetric induction, unusual diastereoselectivity, and the potential use of these reactions in asymmetric synthesis are discussed. Keywords: o-quinodimethanes, Diels–Alder, asymmetric, cycloaddition, induction, diastereoselective.

Asymmetric Synthesis of 2,2,2-Trifluorophenylethanol of High Optical Purity

Synthesis ◽  
1975 ◽  
Vol 1975 (11) ◽  
pp. 701-701 ◽  
Author(s):  
D. NASIPURI ◽  
Pranab K. BHATTACHARYA
Keyword(s):  
Asymmetric Synthesis ◽  
Optical Purity ◽  
High Optical Purity

Total synthesis and establishment of the absolute stereochemistry of (+)-mostueine. Addition of chiral nucleophiles to 3,4-dihydro-2-methyl-9-(p-toluenesulfonyl)-β-carbolinium iodide

1992 ◽  
Vol 70 (12) ◽  
pp. 2922-2928 ◽  
Author(s):  
Allan W. Rey ◽  
Walter A. Szarek ◽  
David B. MacLean
Keyword(s):  
Total Synthesis ◽  
Indole Alkaloid ◽  
Optical Purity ◽  
Ring System ◽  
Asymmetric Induction ◽  
Iminium Salt ◽  
High Optical Purity ◽  
The Absolute ◽  
Absolute Stereochemistry ◽  
Mediated Reduction

A highly convergent synthesis of the pentacyclic indole alkaloid (+)-mostueine (1) is described. The key step involved the coupling of the dianion derived from (1′S)-3-(1′-hydroxyethyl)-4-methylpyridine (4) with the iminium salt 3,4-dihydro-2-methyl-9-(p-toluenesulfonyl)-β-carbolinium iodide (3). Low asymmetric induction (15% de) at the C-1 position of the β-carboline ring system (C-3 of mostueine) was obtained. The nonfermenting baker's yeast-mediated reduction of 3-acetyl-4-methylpyridine provided the hydroxyethylpyridine component in acceptable yield (67%) and high optical purity (99.0% ee). This synthesis of 1 has established that the absolute stereochemistry of mostueine is (3S, 19R).

Glyoxylic acid derivatives in asymmetric synthesis

2000 ◽  
Vol 72 (9) ◽  
pp. 1589-1596 ◽  
Author(s):  
Janusz Jurczak ◽  
Tomasz Bauer
Keyword(s):  
Natural Products ◽  
Asymmetric Synthesis ◽  
Glyoxylic Acid ◽  
Optical Purity ◽  
Organic Syntheses ◽  
High Optical Purity ◽  
Derivatives Of

Synthesis of chiral derivatives of glyoxylic acid with special emphasis on N-glyoxyloyl-(2R)-bornane-10,2-sultam is presented. Investigation of glyoxylic acid chiral derivatives in various stereocontrolled organic syntheses showed their excellent ability to provide products of high optical purity. Application of our methodology to the synthesis of natural products and their analogs is presented.

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