Total synthesis of carbohydrates: stereoselective syntheses of 2,6-dideoxy-D-arabino-hexose and 2,6-dideoxy-D-ribo-hexose

1982 ◽  
Vol 47 (7) ◽  
pp. 1371-1373 ◽  
Author(s):  
William R. Roush ◽  
Richard J. Brown
Keyword(s):  
Total Synthesis ◽  
Stereoselective Syntheses

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 Scytophycin C. 1. Stereoselective Syntheses of the C(1)−C(18) Segment and the C(19)−C(31) Segment

2003 ◽  
Vol 5 (20) ◽  
pp. 3579-3582 ◽  
Author(s):  
Ryoichi Nakamura ◽  
Keiji Tanino ◽  
Masaaki Miyashita
Keyword(s):  
Total Synthesis ◽  
Scytophycin C ◽  
Stereoselective Syntheses

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).

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