Stereoselective Total Synthesis of Copa and Ylango Sesquiterpenoids: Preparation of (−)-(1S,4S,5R,7R)-1,7-Dimethyl-4-isopropylbicyclo[3.2.1]octa-6,8-dione and(+)-(1R,4S,5S,7S)-1,7-Dimethyl-4-isopropylbicyclo[3.2.1]octa-6,8-dione

1975 ◽  
Vol 53 (19) ◽  
pp. 2827-2837 ◽  
Author(s):  
Edward Piers ◽  
Ronald W. Britton ◽  
M. Bert Geraghty ◽  
Robert J. Keziere ◽  
R. Dean Smillie
Keyword(s):  
Total Synthesis ◽  
Acetyl Chloride ◽  
Ester Hydrolysis ◽  
Keto Acid ◽  
Blocking Group ◽  
Claisen Condensation ◽  
Keto Ester ◽  
Enolate Anion ◽  
Stereoselective Syntheses ◽  
Potential Use

The efficient, stereoselective syntheses of two diastereomeric bicyclo[3.2.1]octadiones (23 and 24) are described and the potential use of these materials for the synthesis of the copa (1–5) and the ylango (7–11) sesquiterpenoids, respectively, is outlined. Conversion of (+)-carvomenthone (26) into the corresponding n-butylthiomethylene derivative 28, followed by alkylation of the latter with ethyl 2-iodopropionate, gave compound 29. Removal of the blocking group from the latter was accompanied by ester hydrolysis and afforded keto acid 30. An efficient intramolecular Claisen condensation of the corresponding ester 31 yielded (−)-(1S,4S,5R,7R)-1,7-dimethyl-4-isopropylbicyclo[3.2.1]octa-6,8-dione(23). Conversion of the known octalone 39 into the cross-conjugated keto aldehyde 41 was accomplished by standard reactions. Treatment of the latter with lithium dimethylcuprate, followed by trapping of the resultant enolate anion with acetyl chloride gave compound 42. Oxidative ozonolysis of this material yielded the keto acid 43. Esterification of the latter, followed by intramolecular Claisen condensation of the resulting keto ester 45, afforded (+)-(1R,4S,5S,7S)-1,7-dimethyl-4-isopropylbicyclo[3.2.1]octa-6,8-dione (24).

Stereoselective Total Synthesis of Copa and Ylango Sesquiterpenoids: (+)-Copacamphor, (+)-Copaborneol, (+)-Copaisoborneol, (−)-Ylangocamphor, (−)-Ylangoborneol, (−)-Ylangoisoborneol

1975 ◽  
Vol 53 (19) ◽  
pp. 2838-2848 ◽  
Author(s):  
Edward Piers ◽  
Ronald W. Britton ◽  
M. Bert Geraghty ◽  
Robert J. Keziere ◽  
Fusao Kido
Keyword(s):  
Total Synthesis ◽  
Liquid Ammonia ◽  
Lithium Aluminum Hydride ◽  
Aluminum Hydride ◽  
High Yield ◽  
Lithium Aluminum ◽  
Alkylation Product ◽  
Intramolecular Alkylation ◽  
Enolate Anion ◽  
Stereoselective Syntheses

Efficient, stereoselective syntheses of the tricyclic sesquiterpenoids (+)-copacamphor (3), (+)-copaborneol (4), (+)-copaisoborneol (5), (−)-ylangocamphor (6), (−)-ylangoborneol (7), and (−)-ylangoisoborneol (8) are described. Conversion of the keto acetate 9 (previously synthesized from the dione 1) into the keto tosylate 17 was accomplished via an eight-step sequence. Intramolecular alkylation of 17 afforded, in high yield, (+)-copacamphor (3), which had previously been converted into the corresponding alcohols 4 and 5 by Kolbe-Haugwitz and Westfelt. Alkylation of the enolate anion of the bicyclic dione 2 with 2-bromopropane in hexamethylphosphoramide gave mainly the O-alkylation product 19. Conversion of 19 into the keto mesylate 29 was carried out in 5 synthetic steps. Intramolecular alkylation of 29 afforded (−)-ylangocamphor (6). Reduction of the latter with calcium in liquid ammonia gave (−)-ylangoborneol (7), while reduction with lithium aluminum hydride yielded (−)-ylangoisoborneol (8).

Total Synthesis of Eremophilane-type Sesquiterpenoids: (±)-Eremophilenolide, (±)-Tetrahydroligularenolide, and (±)-Aristolochene

1973 ◽  
Vol 51 (13) ◽  
pp. 2166-2173 ◽  
Author(s):  
Edward Piers ◽  
Michael Bert Geraghty
Keyword(s):  
Total Synthesis ◽  
Keto Acid ◽  
Keto Ester ◽  
Synthetic Intermediate

The total synthesis of the racemic forms of the eremophilane-type sesquiterpenoids eremophilenolide (2), tetrahydroligularenolide (3), and aristolochene (4) is described. The octalone 7 was converted via an efficient, regioselective route into the keto ester 12, which served as a common synthetic intermediate for the preparation of the three sesquiterpenoids. Successive subjection of 12 to alkylation, hydrolysis, and decarboxylation afforded the keto acid 14. Hydrogenation of the latter provided both the cis-fused keto acid 20, which was readily converted into (±)-eremophilenolide (2), and the trans-fused keto acid 15, which was similarly transformed into (±)-tetrahydroligularenolide (3). Conversion of 12 into the dithioketal 23, followed by desulfurization and treatment of the resultant olefinic ester 25 with excess methyllithium, provided the olefinic alcohol 27. Dehydration of the latter yielded (±)-aristolochene (4).

Total synthesis of d,l-coronafacic acid by an intermolecular Diels–Alder approach

1984 ◽  
Vol 62 (9) ◽  
pp. 1747-1750 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Montse Llinas-Brunet
Keyword(s):  
Total Synthesis ◽  
Diels Alder ◽  
Keto Ester ◽  
Coronafacic Acid

An efficient total synthesis of d,l-coronafacic acid (2) has been achieved from 4-cyclopentene-1,3-dione (4). The synthesis involves keto ester 7 as a key intermediate that is conveniently prepared by the Diels–Alder addition of enedione 4 to ethyl 4-ethyl-2,4-pentadienoate (5).

scholarly journals Total synthesis of the endogenous inflammation resolving lipid resolvin D2 using a common lynchpin

2013 ◽  
Vol 9 ◽  
pp. 2762-2766 ◽  
Author(s):  
John Li ◽  
May May Leong ◽  
Alastair Stewart ◽  
Mark A Rizzacasa
Keyword(s):  
Total Synthesis ◽  
Wittig Reaction ◽  
Phosphonium Salt ◽  
Ester Hydrolysis ◽  
Sonogashira Coupling ◽  
Partial Reduction ◽  
Vinyl Iodide ◽  
Key Steps

The total synthesis of the endogenous inflammation resolving eicosanoid resolvin D2 (1) is described. The key steps involved a Wittig reaction between aldehyde 5 and the ylide derived from phosphonium salt 6 to give enyne 17 and condensation of the same ylide with aldehyde 7 to afford enyne 11. Desilylation of 11 followed by hydrozirconation and iodination gave the vinyl iodide 4 and Sonogashira coupling between this compound and enyne 3 provided alkyne 18. Acetonide deprotection, partial reduction and ester hydrolysis then gave resolvin D2 (1).

Total synthesis of androstanes

1979 ◽  
Vol 57 (24) ◽  
pp. 3356-3358 ◽  
Author(s):  
Masatoshi Kakushima ◽  
Jagabandhu Das ◽  
Gary R. Reid ◽  
Peter S. White ◽  
Zdenek Valenta
Keyword(s):  
Total Synthesis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Keto Ester ◽  
Diels Alder Reaction ◽  
Androstane Derivatives

A total synthesis of androstane derivatives is described. The desired configuration at C8 and at C13 is achieved in a ring C forming SnCl4-catalyzed Diels–Alder reaction. The preparation of methyl Z-2-methyl-4-oxo-2-pentenoate and the cyclization of a keto ester to a steroid 15,17-dione are also reported.

Electrophilic cyclization of an olefinic β-keto ester

1981 ◽  
Vol 59 (14) ◽  
pp. 2239-2241 ◽  
Author(s):  
Margot Alderdice ◽  
Larry Weiler
Keyword(s):  
Silica Gel ◽  
Aluminum Chloride ◽  
Cyclization Reaction ◽  
Electrophilic Cyclization ◽  
Keto Ester ◽  
Potential Use

Benzeneselenenyl chloride and aluminum chloride or benzenesulphenyl chloride and silica gel initiate an electrophilic cyclization of methyl 7-methyl-3-oxo-7-octenoate to cyclohexyl derivatives. These products of the cyclization reaction have been converted into intermediates of potential use in the synthesis of unusual carotenoids.

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