Total synthesis of panaxytriol and panaxydiol

The enantioselective total synthesis of the diyne containing natural products panaxytriol and (3S,10R)-panaxydiol from l-tartaric acid is reported. Key steps in the synthesis include the elaboration of a γ-hydroxy amide derived from tartaric acid to the required alkyne and the formation of the desired diyne unit by a Cadiot–Chodkiewicz coupling.

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(S)-2-(Benzyloxy)-1-((4R,5R)-5-heptyl-2,2-dimethyl-1,3-dioxolan-4-yl)ethanolC21H36O4[α]D = +26.1 (c 1.6, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (2S,4R,5R)

O-((S)-2-(Benzyloxy)-1-((4S,5R)-5-heptyl-2,2-dimethyl-1,3-dioxolan-4-yl)ethyl)S-methyl carbonodithioateC23H36O4S2[α]D = –11.5 (c 1.6, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (2S,4R,5R)

(4R,5R)-4-(2-(Benzyloxy)ethyl)-5-heptyl-2,2-dimethyl-1,3-dioxolaneC21H34O3[α]D = +27.2 (c 4.1, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (4R,5R)

2-((4R,5R)-5-Heptyl-2,2-dimethyl-1,3-dioxolan-4-yl)ethanolC14H28O3[α]D = +35.5 (c 1.4, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (4R,5R)

(4R,5R)-4-(3,3-Dibromoallyl)-5-heptyl-2,2-dimethyl-1,3-dioxolaneC15H26Br2O2[α]D = +23.4 (c 2.1, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (4R,5R)

(4R,5R)-4-Heptyl-2,2-dimethyl-5-(prop-2-yn-1-yl)-1,3-dioxolaneC15H26O2[α]D = +15.3 (c 1.4, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (4R,5R)

(4R,5R)-4-(3-Bromoprop-2-yn-1-yl)-5-heptyl-2,2-dimethyl-1,3-dioxolaneC15H25BrO2[α]D = +10.1 (c 2, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (4R,5R)

tert-Butyl(((R)-8-((4R,5R)-5-heptyl-2,2-dimethyl-1,3-dioxolan-4-yl)octa-1-en-4,6-diyn-3-yl)oxy)diphenylsilaneC36H48O3Si[α]D = +119.8 (c 2.8, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (8R,4R,5R)

PanaxytriolC17H26O3[α]D = −17.7 (c 1.2, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (3R,9R,10R)

(R,E)-Dodec-3-en-1-yn-5-olC12H20O[α]D = –14.7 (c 2.1, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (E,5R)

(R,E)-1-Bromododec-3-en-1-yn-5-olC12H19BrO[α]D = +10.5 (c 0.8, CHCl3)Source of chirality: l-(+)-tartaric acidAbsolute configuration: (E,5R)

(8R,15S,E)-15-((tert-Butyldiphenylsilyl)oxy)heptadeca-9,16-dien-11,13-diyn-8-olC33H42O2Si[α]D = +174.6 (c 1.6, CHCl3)Source of chirality: l-(+)-tartaric acid and d-(−)-tartaric acidAbsolute configuration: (8R,15S,E)

(E,3S,10R)-PanaxydiolC17H24O2[α]D = +25.4 (c 0.6, CHCl3)Source of chirality: l-(+)-tartaric acid and d-(−)-tartaric acidAbsolute configuration: (E,3S,10R)