Total synthesis of the marine polypropionates, siphonarienal, siphonarienone, and pectinatone

The synthesis of the marine natural products, siphonarienal, siphonarienone, and pectinatone is described employing desymmetrization strategy to create three consecutive stereogenic centers. The key intermediate 7 was made by asymmetric hydroboration of the known meso-olefin using (−)-IPC2BH followed by PCC and Baeyer-Villiger oxidation reactions.

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(E,4S,6S,8S)-2,4,6,8-Tetramethyl-2-undecenalC15H28O[α]D25=+16.5 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (E,4S,6S,8S)

Siphonarienone, [(E,6S,8S,10S)-4,6,8,10-tetramethyl-4-tridecen-3-one]C17H32O[α]D25=+16.0 (c 1.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (E,6S,8S,10S)

Pectinatone, [4-hydroxy-3,5-dimethyl-6-[(E,3S,5S,7S)-1,3,5,7-tetramethyl-1-decenyl]-2H-2-pyranone]C21H34O3[α]D25=+60.5 (c 0.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (E,3S,5S,7S)

Ethyl (E,4S,6S,8S)-2,4,6,8-tetramethyl-2-undecenoateC17H32O2[α]D25=+26.5 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (E,4S,6S,8S)

(2S,4S,6S)-2,4,6-TrimethylnonanalC12H24O[α]D25=+6.2 (c 0.26, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R,5S,9S)

(2R,3R,4S,5R,6R)-2-Allyl-5-[(4-methoxybenzyl)oxy]-4,6-dimethylheptane-1,3,7-triolC20H32O5[α]D25=+6.0 (c 1.4, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R,4S,5R,6R)

7-(4-Methoxybenzyloxy)-4(2′-propen),6,8-diimethyl-(1S,4S,5S,6S,7S,8R)-2,9-dioxabicyclo-[3.3.1]nonan-3-oneC20H26O5[α]D25=-75 (c 1.3, CHCl3)Source of Chirality: Asymmetric SynthesisAbsolute configuration: (1S,4S,5S,6S,7S,8R)

(2R,3R,4R)-4-[(4R,5R)-5-Allyl-2,2-dimethyl-1,3-dioxan-4-yl]-3-[(4-methoxybenzyl)oxy]-2-methylpentan-1-olC23H36O5[α]D25=-33.0 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R,4R, 4R,5R)

(4R,5R)-5-Allyl-4-(1R,2R,3R)-4-(benzyloxy)-2-[(4-methoxybenzyl)oxy]-1,3-dimethylbutyl-2,2-dimethyl-1,3-dioxaneC30H42O5[α]D25=-18.0 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (4R,5R, 1R,2R,3R)

(2R,3R,4S,5R,6R)-2-Allyl-7-(benzyloxy)-5-[(4-methoxybenzyl)oxy]-4,6-dimethylheptane-1,3-diolC27H38O5[α]D25=+18.0 (c 1.15, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3R,4S,5R,6R)

(4S,5R,6S,7R,8R)-9-(Benzyloxy)-7-[(4-methoxybenzyl)oxy]-4,6,8-trimethyl-1-nonen-5-olC27H38O4[α]D25=+26.6 (c 1.15, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (4S,5R,6S,7R,8R)

(1R,2S)-1-(1R,2R,3R)-4-(Benzyloxy)-2-[(4-methoxybenzyl)oxy]-1,3-dimethylbutyl-2-methyl-4-pentenyl (methylsulfanyl)methanethioateC29H40O4S2[α]D25=+2.3 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (1R,2S,1R,2R,3R)

(4S,6S,7S,8R)-9-(Benzyloxy)-7-[(4-methoxybenzyl)oxy]-4,6,8-trimethyl-1-noneneC27H38O3[α]D25=+12.9 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (4S,6S,7S,8R)

(2R,3S,4S,6S)-1-(Benzyloxy)-2,4,6-trimethyl-8-nonen-3-olC19H30O2[α]D25=-25.0 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2R,3S,4S,6S)

(1S,2S,4S)-1-[(1R)-2-(Benzyloxy)-1-methylethyl]-2,4-dimethyl-6-heptenyl methylsulfanyl)methanethioateC21H32O2S2[α]D25=+11.5 (c 1.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (1S,2S,4S,1R)

(4S,6S,8S)-9-(Benzyloxy)-4,6,8-trimethyl-1-noneneC19H30O[α]D25=+2.9 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (4S,6S,8S)

(2S,4S,6S)-2,4,6-Trimethylnonan-1-olC12H26O[α]D25=+5.2 (c 0.3, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (2S,4S,6S)

(E,4S,6S,8S)-2,4,6,8-Tetramethyl-2-undecen-1-olC15H30O[α]D25=+9.4 (c 0.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (E,4S,6S,8S)

N-1-Methoxy-N-1,2,4,6,8-pentamethyl-(E,4S,6S,8S)-2-undecenamideC17H33NO2[α]D25=+12.0 (c 1.0, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (E,4S,6S,8S)