A Practical, Enantiospecific Synthesis of (S)-Trans-γ-Monocyclofarnesol

2012 ◽  
Vol 7 (12) ◽  
pp. 1934578X1200701 ◽  
Author(s):  
Stefano Serra
Keyword(s):  
Fractional Crystallization ◽  
Good Yield ◽  
Target Compound ◽  
Combined Use ◽  
Enantiospecific Synthesis ◽  
Key Steps ◽  
Very High

An expedient and concise synthesis of (S)-trans-γ-monocyclofarnesol is here described. The aforementioned sesquiterpene was prepared starting from enantioenriched (S)-γ-dihydroionone, which was in turn obtained from racemic α-ionone through the combined use of two previously developed processes. Key steps of the presented synthesis are the stereoselective Horner-Wadsworth-Emmons reaction between triethyl phosphonoacetate and γ-dihydroionone and the effective fractional crystallization of the γ-monocyclofarnesol-3,5-dinitrobenzoate esters. By these means the target compound was obtained in good yield and with very high stereoisomeric purity.

First Total Synthesis of a Fluorinated Calystegin

2010 ◽  
Vol 65 (4) ◽  
pp. 445-451 ◽  
Author(s):  
René Csuk ◽  
Erik Prell ◽  
Stefan Reißmann ◽  
Claudia Korb
Keyword(s):  
Total Synthesis ◽  
Ring Opening ◽  
Competitive Inhibitor ◽  
Ring Closure ◽  
Target Compound ◽  
Metathesis Reaction ◽  
Grubbs Catalyst ◽  
Ring Opening Reaction ◽  
Ultrasound Assisted ◽  
Key Steps

A straightforward chiral pool synthesis for the first fluorinated calystegin is described. Key steps of this synthesis include an ultrasound-assisted Zn-mediated tandem ring opening reaction followed by a Grubbs’ catalyst-mediated ring closure metathesis reaction. The target compound is a selective and competitive inhibitor for a β -glycosidase.

Annulations leading to diene systems. Total syntheses of the dolastane-type diterpenoids (±)-(5S,12R,14S)-dolasta-1(15),7,9-trien-14-ol and (±)-amijitrienol

1992 ◽  
Vol 70 (4) ◽  
pp. 1204-1220 ◽  
Author(s):  
Edward Piers ◽  
Richard W. Friesen
Keyword(s):  
Aldol Condensation ◽  
Ring Closure ◽  
Starting Material ◽  
Target Compound ◽  
One Pot ◽  
Stereoselective Reduction ◽  
Total Syntheses ◽  
Reductive Transformation ◽  
The One ◽  
Key Steps

Alkylation of the substituted cycloalkanones 14a–d and 30 with (Z)-1-bromo-4-methyl-3-trimethylstannyl-2-pentene (13) produced compounds 15a–d and 33, which were readily converted into the corresponding enol trifluoromethane-sulfonates (triflates) 16a–d and 34. Intramolecular Pd(O)-catalyzed coupling of the vinylstannane and enol triflate functions in 16a–d and 34 provided the dienes 17a–d and 35. The annulation product 35 served as a suitable starting material for the total syntheses of the dolastane diterpenoids (±)-(5S,12R,14S)-dolasta-1(15),7,9-trien-14-ol (2) and (±)-amijitrienol (3). The key steps of the synthesis of (±)-2 involved the stereoselective methylation of the ketone 44 (readily derived from 35) to provide 46 and the Barbier type ring closure of 47 to provide the target compound. For the synthesis of (±)-3, the notable conversions included the reductive transformation of the diene 35 into the alkene 53, the aldol condensation of the ketone 54 with 4-trimethylstannyl-4-pentenal (55), the chemo- and stereoselective reduction of the dione 58, and the one-pot conversion of the keto vinylstannane 63 into the triene 65, via the intermediate 64.

scholarly journals Synthesis of the Trans-Syn-Trans Perhydrobenzo[f]chromene Ring System

2021 ◽  
Author(s):  
Amjad Ayad Qatran AlKhdhairawi ◽  
Syahrul Imran ◽  
Nurhuda Manshoor ◽  
Geoffrey A. Cordell ◽  
Narendra Babu Shivanagere Nagojappa ◽  
...  
Keyword(s):  
Stereoselective Synthesis ◽  
Ring System ◽  
Unsaturated Ketone ◽  
Target Compound ◽  
Reductive Alkylation ◽  
Acid Catalyzed ◽  
Key Steps ◽  
Chromene Ring

<p>A stereoselective synthesis of the <i>trans</i>-<i>syn</i>-<i>trans </i>perhydrobenzo[<i>f</i>]chromene skeleton is presented. The target compound <b>3 </b>was achieved in six steps starting from the (<i>S</i>)-(+)-Wieland-Miescher ketone. Key steps include the sp<sup>2</sup> alkylation at the a-carbon of an unsaturated ketone, Birch-type reductive alkylation, and an acid-catalyzed cyclization. </p>

scholarly journals SOLVENT-FREE SYNTHESIS OF AMIDE: A NOVEL TECHNIQUE OF GREEN CHEMISTRY

2021 ◽  
pp. 99-102
Author(s):  
CHIRAGKUMAR J GOHIL ◽  
MALLESHAPPA N NOOLVI
Keyword(s):  
Carboxylic Acid ◽  
Green Chemistry ◽  
Good Yield ◽  
Functional Group ◽  
Environmental Issues ◽  
Solvent Free ◽  
Novel Technique ◽  
Rate Of Reaction ◽  
Solvent Free Synthesis ◽  
Very High

Objective: Amide is one of the most important functional group presents in the chemicals, pharmaceuticals, and foods. Conventionally, it has been synthesized from the carboxylic acid and amines. This conventional reaction is lengthy and involves hazardous chemicals and solvents. Hence, it poses waste management, solvent removal, and environmental issues to the industries. To overcome this limitation, we have reported the green chemistry-based method for the synthesis of amide from carboxylic acid and urea. Methods: In this reaction, we have used boric acid as a catalyst, it is a simple and readily available compound. It is simple, efficient, and solvent-free procedure which involves the trituration of the reactant mixture and subsequent, direct heating of the triturated mixture. Results: The rate of reaction is very high and can synthesize the amide quickly. Conclusion: Various amides were prepared in good yield by this technique.

Stereoselective Synthesis of Spiro-α-methylene-γ-lactams via Chiral Quaternary 3-Aminooxindole Adducts Accessed by Zn-Mediated Allylation of Sulfinyl Ketimines

Synthesis ◽  
2020 ◽  
Vol 52 (17) ◽  
pp. 2551-2562 ◽  
Author(s):  
Ravi P. Singh ◽  
V. U. Bhaskara Rao ◽  
Shashank Singh ◽  
Krishna N. Tripathi
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Efficient Method ◽  
Good Yield ◽  
Stereoselective Synthesis ◽  
High Selectivity ◽  
X Ray ◽  
Relative Stereochemistry ◽  
Very High

An efficient method for the stereoselective synthesis of α-methylene-γ-lactams via quaternary 3-aminooxindoles with very high selectivity (up to 98% ee) is described. The methodology leads to the construction of sterically congested chiral quaternary 3-aminooxindole adducts in good yield and with moderate to excellent diastereoselectivity (dr up to 95:5). The relative stereochemistry of the chiral quaternary 3-aminooxindoles adduct and the spiro-α-methylene-γ-lactam was confirmed to be syn by single-crystal X-ray structure analysis. Furthermore, the α-methylene-γ-lactam was successfully transformed into a range of chiral synthons.

scholarly journals Diastereoselective Synthesis of (–)-Bestatin, Epibestatin, Phebestin and (3S,4R)-4-Amino-3-hydroxy-5-phenylpentanoic Acid from an Aldehyde Derived from d-Phenylalanine

SynOpen ◽  
2019 ◽  
Vol 03 (04) ◽  
pp. 114-123
Author(s):  
Vipin Kumar Jain
Keyword(s):  
Amino Acid ◽  
Efficient Method ◽  
Good Yield ◽  
Starting Material ◽  
Hydroxyl Group ◽  
Diastereoselective Synthesis ◽  
Synthetic Route ◽  
Protected Amino Acid ◽  
Very High ◽  
General Method

A convenient and efficient method for the synthesis of (–)-bestatin, epibestatin, phebestin, and (3S,4R)-4-amino-3-hydroxy-5-phenylpentanoic acid is reported. The key step is a proline-catalyzed α-hydroxylation of an aldehyde derived from d-phenylalanine, which leads to incorporation of a hydroxyl group at the α-position of that aldehyde with good yield and very high diastereoselectivity. Bestatin and its dia­stereomer epibestatin are synthesized from the same starting material using the same sequence of reactions, except for proline as the catalyst. An O-MOM and Boc-protected amino acid, a common intermediate for bestatin, was coupled with a dipeptide, H-Val-Phe-OMe followed by global deprotection to yield phebestin. (3S,4R)-4-Amino-3-hydroxy-5-phenylpentanoic acid was also synthesized in eight steps from the same starting material. The reported synthetic route offers a general method for the synthesis of such types of compounds and their analogues by changing the proline catalyst and/or the starting material from d- to l-phenylalanine.

Reactions of organic compounds in adsorbed monolayers. I. Ozonation of 3,7-dimethyloctyl acetate

1977 ◽  
Vol 30 (10) ◽  
pp. 2177 ◽  
Author(s):  
ALJ Beckwith ◽  
CL Bodkin ◽  
T Duong
Keyword(s):  
Organic Compounds ◽  
Good Yield ◽  
Steric Effect ◽  
Barium Sulphate ◽  
Organic Substrate ◽  
The Other ◽  
Hydroxy Compound ◽  
Experimental Conditions ◽  
Adsorbed Monolayer ◽  
Very High

Oxidation with ozone of 3,7-dimethyloctyl acetate (7) adsorbed on silica gel, alumina or barium sulphate proceeds in good yield and affords mainly the 7-hydroxy compound (8) and the 7-nor-ketone (9). Minor products include the 3-alcohol (10) and the 3,7-diol (11). The reaction involves interaction of gaseous ozone with the adsorbed organic substrate. The relative yields of the various products are related to the substrate loading. The results show that the very high regioselectivity exhibited by the reaction when conducted under suitable experimental conditions may be attributed to the mutual steric effect of one molecule upon the other in the adsorbed monolayer.

scholarly journals Ultrasonicated Synthesis ofN-Benzyl-2,3-substituted Morpholines, via the Mitsunobu Diol Cyclisation

2010 ◽  
Vol 7 (4) ◽  
pp. 1184-1189
Author(s):  
B. Jayachandra Reddy ◽  
M. C. Somasekhara Reddy
Keyword(s):  
Column Chromatography ◽  
Good Yield ◽  
Mitsunobu Reaction ◽  
Microwave Assisted ◽  
Chemical Studies ◽  
Key Steps

A facile five step synthesis ofN-benzyl-2,3-substituted morpholines (i-iii) was performed. The key steps were microwave assisted Friedel-crafts acylation and diol cyclization carried out via an ultra sonication of Mitsunobu reaction using DEAD (diethylazodicarboxylate), TPP in THF for 1 h. The morpholine products were generated as diasteriomers (iiandiii) which has been separated by the column chromatography to good yield. The structure of compounds (i-iii) has been characterized by the spectral and chemical studies.

Synthesis of 1,2-dicyanoferrocene by cyanation reactions

2020 ◽  
Vol 24 (05n07) ◽  
pp. 786-793
Author(s):  
Diana-Paola Medina ◽  
Javier Fernández-Ariza ◽  
M. Salomé Rodríguez-Morgade ◽  
Tomás Torres
Keyword(s):  
Target Compound ◽  
Step Procedure ◽  
Biphasic Medium ◽  
Key Steps

We report two synthetic pathways for the preparation of 1,2-dicyanoferrocene, in a search for new dinitrile-based precursors that could be useful in the synthesis of metallocene-containing azaporphyrins, as well as in catalysis. Both procedures include cyanation reactions as the key steps. Magnesiation of cyanoferrocene, followed by reaction with electrophilic tosyl cyanide, affords the target compound in only two synthetic steps from ferrocene. In addition, 1,2-dicyanoferrocene can be prepared by a three step procedure, which implies a twofold cyanation of 1,2-dibromoferrocene, using Zn(CN)[Formula: see text], in a biphasic medium and in the presence of bulky [Formula: see text]-BuXPhos-Pd-G3.

scholarly journals Conversion of (−)-α-santonin into (+)-α-cyperone

1968 ◽  
Vol 46 (3) ◽  
pp. 377-383 ◽  
Author(s):  
Edward Piers ◽  
Kin Fai Cheng
Keyword(s):  
Good Yield ◽  
Homogeneous Catalyst ◽  
Keto Ester ◽  
Key Steps

An efficient, 8-step synthesis of (+)-α-cyperone (1) from (−)-α-santonin (5) is described. The key steps of the sequence involve the conversion of the keto ester 8 into the substituted octalone 9, by hydrogenation of the former in the presence of the homogeneous catalyst tris(triphenylphosphine)-chlororhodium, and the pyrolysis of the keto carbonate 16, which produces (+)-α-cyperone in good yield.

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