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).

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).

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).

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.

Total synthesis of amphilectane-type diterpenoids: (±)-8,15-diisocyano-11(20)-amphilectene

1993 ◽  
Vol 71 (9) ◽  
pp. 1484-1494 ◽  
Author(s):  
Edward Piers ◽  
Montse Llinas-Brunet ◽  
Renata M. Oballa
Keyword(s):  
Total Synthesis ◽  
Alder Reaction ◽  
Diels Alder ◽  
Allylic Oxidation ◽  
Keto Ester ◽  
Efficient Transformation ◽  
Diels Alder Reaction ◽  
Product Mixture

A total synthesis of the structurally novel, antimicrobial diterpenoid (±)-8,15-diisocyano-11(20)-amphilectene (2) is described. Alkylation of 2-methoxycarbonyl-3-methylcyclohexanone (13) with (E)-1-(tert-butyldimethylsiloxy)-6-iodo-3-(trimethylstannyl)-2-hexene (14) provided, stereoselectively, the functionalized keto ester 15, which was converted efficiently into the diene 17. Diels–Alder reaction of 17 with acrolein, followed by base-catalyzed equilibration of the resultant product mixture, gave the aldehydes 19 (58%) and 20 (29%). Allylic oxidation of the alkene 24 (derived from 19) afforded the enone 25. Reduction (Na, NH3, t-BuOH) of 25 gave 28, which was converted, via a sequence of eight synthetic steps, into the diacid 45. Efficient transformation of the carboxyl functions of 45 into isonitrile groups completed the synthesis of (±)-2.

scholarly journals Total Synthesis of Epothilones B and D: Stannane Equivalents for β-Keto Ester Dianions

2008 ◽  
Vol 73 (24) ◽  
pp. 9675-9691 ◽  
Author(s):  
Gary E. Keck ◽  
Robert L. Giles ◽  
Victor J. Cee ◽  
Carrie A. Wager ◽  
Tao Yu ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Keto Ester

Synthesis of l,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acids and homologous pyridine and azepine analogues thereof

1982 ◽  
Vol 60 (18) ◽  
pp. 2295-2312 ◽  
Author(s):  
Humberto Carpio ◽  
Edvige Galeazzi ◽  
Robert Greenhouse ◽  
Angel Guzmán ◽  
Esperanza Velarde ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Acid Derivative ◽  
Sodium Borohydride ◽  
Acid Ester ◽  
Keto Acid ◽  
Acid Salt ◽  
Keto Ester ◽  
Acetic Acid Esters ◽  
Acid Esters

Several syntheses of the previously unknown 1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acid and various 5- and 6-substituted derivatives thereof have been devised. Some of these processes have been extended to the heretofore unreported 5,6,7,8-tetrahydropyrrolo[1,2-a]pyridine-8-carboxylic acid and 5,6,7,8-tetrahydro-9H-pyrrolo[1,2-a]azepine-9-carboxylic acid derivatives.Two new processes were developed for the conversion of pyrroles into the corresponding pyrrol-2-acetic acid esters. Both processes were based on the use of the readily available ethoxalylpyrrole derivatives as the starting material. One sequence involved saponification of the α-keto ester, followed by Wolff–Kishner reduction of the crude α-keto acid salt and subsequent esterification of the acetic acid derivative thus produced. The second synthesis commenced with reduction of the 2-ethoxalpyrrole with sodium borohydride to the α-hydroxy ester, which was further reduced to the acetic acid ester with an equimolar mixture of triphenylphosphine and triphenylphosphine diiodide.

Sign in / Sign up

Export Citation Format

Share Document