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.

First Total Synthesis of 3-Epi-calystegin B2

2011 ◽  
Vol 66 (3) ◽  
pp. 317-323
Author(s):  
René Csuk ◽  
Stefan Reißmann ◽  
Ralph Kluge ◽  
Dieter Ströhl ◽  
Claudia Korb
Keyword(s):  
Total Synthesis ◽  
Ring Opening ◽  
Tight Binding ◽  
Ring Closure ◽  
Hydroxyl Group ◽  
Target Compound ◽  
Metathesis Reaction ◽  
Ring Opening Reaction ◽  
Ultrasound Assisted ◽  
Key Steps

A straightforward chiral pool synthesis for a non-natural calystegin, 3-epi-B2, 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. Compared to calystegin B2, the target compound is no longer an inhibitor for a β -glycosidase hence proving that an equatorial hydroxyl group at position C-3 is necessary for a tight binding of calystegins into the active site of β -glycosidases.

Studies on the Total Synthesis of Antibiotic Macrolactin S: A Conventional Approach for the Synthesis of the C1–C9 and C10–C24 Fragments

Synthesis ◽  
2017 ◽  
Vol 50 (03) ◽  
pp. 663-675
Author(s):  
Pabbaraja Srihari ◽  
Ramakrishna Sayini
Keyword(s):  
Total Synthesis ◽  
Nucleophilic Addition ◽  
Ring Opening ◽  
Addition Reaction ◽  
Epoxide Ring ◽  
Epoxide Ring Opening ◽  
Ring Opening Reaction ◽  
Nucleophilic Addition Reaction ◽  
Convergent Approach ◽  
Key Steps

The C1–C9 and C10–C24 segments of the 24-membered polyene macrolide macrolactin S were synthesized by routes involving an epoxide-ring-opening reaction, an Ohira–Bestmann alkyne formation, a chelation-controlled nucleophilic addition reaction, and a Still–Gennari olefination as key steps. A chiron approach , starting from readily available glucose diacetonide, was used to synthesize a key intermediate, and a convergent approach was adopted for the synthesis of the key C10–C24 fragment.

Total Synthesis of Resolvin T4

Synlett ◽  
2021 ◽  
Author(s):  
Narihito Ogawa ◽  
Kohei Arai ◽  
Yuichi Kobayashi
Keyword(s):  
Total Synthesis ◽  
Ring Opening ◽  
Transfer Hydrogenation ◽  
Asymmetric Transfer Hydrogenation ◽  
Ring Opening Reaction ◽  
Propargylic Alcohol ◽  
Chiral Centers ◽  
Wittig Reactions

AbstractA total synthesis of resolvin T4 was achieved by connecting three intermediates by Wittig reactions. The enal in the C1–C10 part was constructed through reduction of a propargylic alcohol with Red-Al followed by oxidation. The enal moiety in the C11–C16 part was synthesized by a ring-opening reaction of a silyl epoxide followed by a Peterson elimination. The chiral centers at C7 and C13 were constructed by ruthenium-catalyzed asymmetric transfer hydrogenation.

Thermal intramolecular reactions of Δ1-1,2,4-triazolines with extended exocyclic unsaturation

1988 ◽  
Vol 66 (3) ◽  
pp. 385-390 ◽  
Author(s):  
Adrian L. Schwan ◽  
John Warkentin
Keyword(s):  
Ring Opening ◽  
Hydrolysis Product ◽  
Sigmatropic Rearrangement ◽  
Membered Ring ◽  
Ring Closure ◽  
Experimental Results ◽  
First Order ◽  
Ring Opening Reaction ◽  
Intramolecular Reactions

Fumaratotriazoline (1) and amidotriazoline (3) undergo thermal first-order transformations in solution at 65 °C. The former affords the isomeric pyrrole 5 and its hydrolysis product 6. A mechanism involving opening of the initial five-membered ring to form 8, followed by closure to a new five-membered ring (9), is proposed. Amidotriazoline (3) loses N2 on heating to form 19. The experimental results are best accommodated in terms of a novel mechanism involving an electrocyclic ring closure, a [3 + 2] cycloreversion to form an ylide, a sigmatropic rearrangement of the ylide, and, finally, an electrocyclic ring-opening reaction.

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 Bidirectional cross metathesis and ring-closing metathesis/ring opening of a C 2-symmetric building block: a strategy for the synthesis of decanolide natural products

2013 ◽  
Vol 9 ◽  
pp. 2544-2555 ◽  
Author(s):  
Bernd Schmidt ◽  
Oliver Kunz
Keyword(s):  
Building Block ◽  
Ring Opening ◽  
Kinetic Resolution ◽  
Membered Ring ◽  
Ring Closure ◽  
Ring Closing Metathesis ◽  
Cross Metathesis ◽  
Key Steps ◽  
A Site ◽  
Site Selective

Starting from the conveniently available ex-chiral pool building block (R,R)-hexa-1,5-diene-3,4-diol, the ten-membered ring lactones stagonolide E and curvulide A were synthesized using a bidirectional olefin-metathesis functionalization of the terminal double bonds. Key steps are (i) a site-selective cross metathesis, (ii) a highly diastereoselective extended tethered RCM to furnish a (Z,E)-configured dienyl carboxylic acid and (iii) a Ru–lipase-catalyzed dynamic kinetic resolution to establish the desired configuration at C9. Ring closure was accomplished by macrolactonization. Curvulide A was synthesized from stagonolide E through Sharpless epoxidation.

Intermediates from ring-opening reactions. Reactions of 2-chloro-5-nitropyridine and 2-chloro-3-nitropyridine with deuteroxide ion in selected solvents

1984 ◽  
Vol 62 (6) ◽  
pp. 1120-1123 ◽  
Author(s):  
John D. Reinheimer ◽  
Nicolas Sourbatis ◽  
Robert L. Lavallee ◽  
Douglas Goodwin ◽  
George L. Gould
Keyword(s):  
Ring Opening ◽  
Pyridine Ring ◽  
Ring Closure ◽  
Polar Solvents ◽  
Open Chain ◽  
Decomposition Products ◽  
Aqueous Sodium ◽  
Ring Opening Reaction ◽  
Ring Opening Reactions ◽  
Kinetics Of

Open chain intermediates from the ring-opening reaction of aqueous sodium deuteroxide (2 mol) with 2-chloro-5-nitropyridine (1 mol) and 2-chloro-3-nitropyridine (1 mol) were isolated. These intermediates were purified, analyzed for elemental composition, and characterized by various spectrophotometric techniques. The intermediate formed from 2-chloro-5-nitropyridine and two equivalents of deuteroxide ion reacts with additional deuteroxide in D2O in various polar solvents to reclose the pyridine ring. The kinetics of the ring closure reaction are reported and are supplemented with observations of salt and solvent effects upon the rate of closure. In addition, a mechanism for the ring closure is presented. The intermediate formed from 2-chloro-3-nitropyridine did not undergo a similar ring closure when reacted with additional deuteroxide, but instead formed various decomposition products. A reason for the failure of this ring closure is suggested.

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