A short synthesis of both enantiomers of enterolactone

2000 ◽  
Vol 78 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Mukund P Sibi ◽  
Pingrong Liu ◽  
Michael D Johnson
Keyword(s):  
Key Words ◽  
Enantioselective Synthesis ◽  
Efficient Synthesis ◽  
Short Synthesis

A short and efficient synthesis of both enantiomers of enterolactone, a mammalian lignan, is described. The overall yield for the natural enterolactone, over seven steps, was 19% and for its enantiomer 27%. Key words: enterolactone, 4-diphenylmethyl-2-oxazolidinone, succinate, enantioselective synthesis.

Enantioselective synthesis of (R)-tolterodine using lithiation/borylation–protodeboronation methodology

2012 ◽  
Vol 90 (11) ◽  
pp. 965-974 ◽  
Author(s):  
Stefan Roesner ◽  
Varinder K. Aggarwal
Keyword(s):  
Enantioselective Synthesis ◽  
High Yield ◽  
Magnesium Bromide ◽  
Efficient Synthesis ◽  
Boronic Ester ◽  
Better Than

The synthesis of the pharmaceutical (R)-tolterodine is reported using lithiation/borylation–protodeboronation of a homoallyl carbamate as the key step. This step was tested with two permutations: an electron-neutral aryl Li-carbamate reacting with an electron-rich boronic ester and an electron-rich aryl Li-carbamate reacting with an electron-neutral boronic ester. It was found that the latter arrangement was considerably better than the former. Further improvements were achieved using magnesium bromide in methanol leading to a process that gave high yield and high enantioselectivity in the lithiation/borylation reaction. The key step was used in an efficient synthesis of (R)-tolterodine in a total of eight steps in a 30% overall yield and 90% ee.

scholarly journals Simple and efficient synthesis of bicyclic enol-carbamates: access to brabantamides and their analogues

RSC Advances ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 6790-6793
Author(s):  
Ondrej Záborský ◽  
Ľudmila Petrovičová ◽  
Jana Doháňošová ◽  
Ján Moncol ◽  
Róbert Fischer
Keyword(s):  
Efficient Synthesis ◽  
Short Synthesis

A simple and short synthesis of bicyclic enol-carbamates with high E/Z selectivity and the synthesis of brabantamide A analogue are presented.

Efficient synthesis of the nonamannoside residue of high mannose glycoproteins

2005 ◽  
Vol 83 (6-7) ◽  
pp. 693-701 ◽  
Author(s):  
Lu Jiang ◽  
Tak Hang Chan
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Key Words ◽  
Building Blocks ◽  
Polymer Support ◽  
Low Molecular Weight ◽  
Oligosaccharide Synthesis ◽  
Efficient Synthesis ◽  
Solution Synthesis ◽  
High Mannose

An efficient synthesis of the nonamannoside residue 1 of high mannose glycoproteins was achieved using an oligomer-supported solution synthesis with low-molecular-weight polyethylene glycol as the anchor. The synthesis required only five coupling steps from only two monosaccharide building blocks with an overall yield of 12%.Key words: nonamannoside, oligosaccharide synthesis, soluble polymer support synthesis, glycoproteins.

Diastereoselective addition of chlorotitanium enolates of N-acyl thiazolidinethione to activated imines — A novel synthesis of β-lactams

2006 ◽  
Vol 84 (12) ◽  
pp. 1696-1699 ◽  
Author(s):  
Marike Herold-Dublin ◽  
Dennis C Liotta
Keyword(s):  
Key Words ◽  
Lewis Acids ◽  
Cholesterol Absorption ◽  
Efficient Synthesis ◽  
Enantiomerically Pure ◽  
Novel Synthesis ◽  
Cholesterol Absorption Inhibitor ◽  
Diastereoselective Addition

We report a novel methodology for preparing enantiomerically pure β-lactams, starting from nitriles in diastereomeric ratios up to 10:1. The power of the methodology was demonstrated by the efficient synthesis of the cholesterol absorption inhibitor SCH 48462.Key words: β-lactam, N-metalloaldimine, titanium Lewis acids, cholesterol absorption inhibitor.

scholarly journals Total Synthesis of Nine Longiborneol Sesquiterpenoids Using a Functionalized Camphor Strategy

2021 ◽  
Author(s):  
Robert F. Lusi ◽  
Goh Sennari ◽  
Richmond Sarpong
Keyword(s):  
Chemical Synthesis ◽  
Total Synthesis ◽  
Natural Product ◽  
Late Stage ◽  
Strategy Development ◽  
Topological Complexity ◽  
Efficient Synthesis ◽  
Short Synthesis ◽  
Synthesis Routes ◽  
The 1960S

<p>Natural product total synthesis inspires strategy development in chemical synthesis. In the 1960s, Corey and coworkers demonstrated a visionary preparation of the terpenoid longifolene, using “strategic bond analysis” to craft a synthesis route. This approach proposes that efficient synthesis routes to bridged, polycyclic, structures should be formulated to introduce the bulk of the target’s topological complexity at a late stage. In subsequent decades, similar strategies have proved general for the syntheses of a wide variety of bridged, polycyclic molecules. Here, we demonstrate that an orthogonal strategy, which utilizes a topologically complex bicyclo[2.2.1] starting material accessed through a scaffold rearrangement of (<i>S</i>)-carvone, leads to a remarkably short synthesis of the longifolene-related terpenoid longiborneol. We also employ a variety of late-stage C–H functionalization tactics in divergent syntheses of many longiborneol congeners. Our strategy should prove effective for the preparation of other topologically complex natural products that contain the bicyclo[2.2.1] framework.</p>

Versatile Enantioselective Synthesis of Four Diastereomers of Serricornin, a Sex Pheromone of the Cigarette Beetle, Using the SAMP/RAMP-Hydrazone Method

2000 ◽  
Vol 65 (4) ◽  
pp. 524-538 ◽  
Author(s):  
Andreas Job ◽  
René Nagelsdiek ◽  
Dieter Enders
Keyword(s):  
Sex Pheromone ◽  
Enantioselective Synthesis ◽  
Starting Material ◽  
Lasioderma Serricorne ◽  
Diethyl Ketone ◽  
Cigarette Beetle ◽  
Stereogenic Centers ◽  
Short Synthesis ◽  
Derivatives Of

Serricornin is a female-produced sex pheromone of the cigarette beetle (Lasioderma serricorne), which is a pest of dried foodstuffs and tobacco. We report a versatile and short synthesis of all possible 6,7-syn-isomers of serricornin, including the natural isomer. Starting from the SAMP and RAMP derivatives of diethyl ketone we obtained four different enantiopure and diastereomerically pure serricornins. The main advantage of this method is that only a single kind of chiral starting material is needed for the construction of three stereogenic centers. During the synthesis further useful intermediates including (R)- and (S)-1-benzyloxy-2-methylpentan-3-one (4) and (2S,3R)- and (2R,3S)-1-iodo-3-(methoxy- methoxy)-2-methylpentane (9) were obtained.

Intramolecular amidation — An efficient synthesis of 3-aryl-2-quinolinones

2006 ◽  
Vol 84 (12) ◽  
pp. 1620-1625 ◽  
Author(s):  
Yinggang Luo ◽  
Feiyan Tao ◽  
Yan Liu ◽  
Bogang Li ◽  
Guolin Zhang
Keyword(s):  
Key Words ◽  
Functional Groups ◽  
Organic Solvents ◽  
Reaction Temperature ◽  
Efficient Synthesis ◽  
Efficient Procedure ◽  
Condensation Products ◽  
Phenyl Rings ◽  
Key Words 3 ◽  
Intramolecular Amidation

To reveal the scope of the syntheses of 3-aryl-2-quinolinones from 2-nitro-α-phenylcinnamic acids, the isomerization of (E)-2-amino-α-phenylcinnamic acids was studied. The results showed that (E)-2-amino-α-phenylcinnamic acids were isomerized to its (Z)-forms under sunlight in organic solvents. The reaction temperature and the functional groups at both phenyl rings have no effect on the isomerization of (E)-2-amino-α-phenylcinnamic acids and the following intramolecular spontaneous amidation of (Z)-2-amino-α-phenylcinnamic acids. Various 3-aryl-2-quinolinones prepared in high total yields indicated that the syntheses of 3-aryl-2-quinolinones from Perkin condensation products 2-nitro-α-phenylcinnamic acids via reduction, sunlight-induced isomerization of (E)-2-amino-α-phenylcinnamic acids, and the following intramolecular amidation is an efficient procedure. Key words: 3-aryl-2-quinolinones, isomerization, amidation.

The synthesis of nor- and bisnorlupanes

1991 ◽  
Vol 69 (3) ◽  
pp. 570-577 ◽  
Author(s):  
Amal Wahhab ◽  
Margaret Ottosen ◽  
Frank W. Bachelor
Keyword(s):  
Quantitative Determination ◽  
Key Words ◽  
Ring Closure ◽  
Efficient Synthesis ◽  
Geological Samples ◽  
Oil Shales

In the course of our studies on geochemical biomarkers we required a series of lupane standards. We report here an efficient synthesis of lupane (1) in three steps from betulin (3) in an overall yield of 47.2%. 17β(H)-28-Norlupane (2) was obtained in 90% purity employing Barton's method for the decarboxylation of 3-oxolupan-28-oic acid (10). 24,28-Bisnorlupane (4) and 24-norlupane (5) were obtained by a series of reactions involving formation of the oxime, the seconitrile, the epoxynitrile, ring closure, and finally a Wolff–Kishner reduction of the C3 carbonyl to the methylene. Also, to aid in the quantitative determination of these lupanes from oil shales and geological samples, 3-deuterolupane (6) and 2,3-dideuterolupane (7) were needed, and a method for their preparation is reported. Key words: lupane, 24-norlupane, 28-norlupane, 24,28-bisnorlupane, 3-deuterolupane, 2,3-dideuterolupane.

scholarly journals A Bifunctional Iminophosphorane Squaramide Catalyzed Enantioselective Synthesis of Hydroquinazolines via Intramolecular Aza-Michael Reaction to α,β-Unsaturated Esters

2021 ◽  
Author(s):  
guanglong su ◽  
Connor J Thompson ◽  
Ken Yamazaki ◽  
Daniel Rozsar ◽  
Kirsten Christensen ◽  
...  
Keyword(s):  
Michael Reaction ◽  
Enantioselective Synthesis ◽  
Efficient Synthesis ◽  
Unsaturated Esters ◽  
High Degree

An efficient synthesis of enantioenriched hydroquinazoline cores via a novel bifunctional iminophosphorane squaramide catalyzed intramolecular aza-Michael reaction of urea-linked α,β-unsaturated esters, is described. The methodology exhibits a high degree of...

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