A new diastereoselective entry to the (1S,4R)- and (1S,4S)-isomers of 4-isopropyl-1-methyl-2-cyclohexen-1-ol, aggregation pheromones of the ambrosia beetle Platypus quercivorus

A concise diastereoselective and enantiopure route to the (1S,4R)- and (1S, 4S)-isomers of 4-isopropyl-1-methyl-2-cyclohexen-1-ol via a palladium-catalysed deoxygenation of the enol triflate derived from limonene glycol.

Figure optionsDownload as PowerPoint slide

(2S,5S)-2-Hydroxy-2-methyl-5-(prop-1-en-2-yl)cyclohexanoneC10H16O2Ee = 99%[α]D20=+2.5 (c 1.0, CHCl3).Source of chirality: (−)-limonene oxideAbsolute configuration: (2S,5S)

(2S,5R)-2-Hydroxy-2-methyl-5-(prop-1-en-2-yl)cyclohexanoneC10H16O2Ee = 98%[α]D20=-49.2 (c 1.1, CHCl3).Source of chirality: (+)-limonene oxideAbsolute configuration: (2S,5R)

(2S,5S)-2-(tert-Butyldimethylsilyloxy)-2-methyl-5-(prop-1-en-2-yl)cyclohexanoneC16H30O2SiEe = 99%[α]D20=-41.3 (c 2.3 CHCl3).Source of chirality: (−)-limonene oxideAbsolute configuration: (2S,5S)

(2S,5R)-2-(tert-Butyldimethylsilyloxy)-2-methyl-5-(prop-1-en-2-yl)cyclohexanoneC16H30O2SiEe = 98%[α]D20=+59.8 (c 1.25, CHCl3).Source of chirality: (+)-limonene oxideAbsolute configuration: (2S,5R)

(3S,6S)-6-(tert-Butyldimethylsilyloxy)-6-methyl-3-(prop-1-en-2-yl)cyclohex-1-enyl trifluoromethane-sulfonateC17H29F3O4SSiEe = 99%[α]D20=-66.15 (c 1.1, CHCl3).Source of chirality: (−)-limonene oxideAbsolute configuration: (3S,6S)

(3R,6S)-6-(tert-Butyldimethylsilyloxy)-6-methyl-3-(prop-1-en-2-yl)cyclohex-1-enyl trifluoromethane-sulfonateC17H29F3O4SSiEe = 98%[α]D20=+5.8 (c 1.25, CHCl3).Source of chirality: (+)-limonene oxideAbsolute configuration: (3R,6S)

(3R,6S)-6-tert-Butyldimethylsilyloxy)-3-isopropyl-6-methylcyclohex-1-enyl trifluoromethanesulfonateC17H31F3O4SSiEe = 99%[α]D20=-21.7 (c 2.65, CHCl3).Source of chirality: (−)-limonene oxideAbsolute configuration: (3R,6S)

(3S,6S)-6-tert-Butyldimethylsilyloxy)-3-isopropyl-6-methylcyclohex-1-enyl trifluoromethanesulfonateC17H31F3O4SSiEe = 98%[α]D20=-35.5 (c 1.55, CHCl3).Source of chirality: (+)-limonene oxideAbsolute configuration: (3S,6S)

(1S,4R)-tert-Butyl((1S,4S)-4-isopropyl-1-methylcyclohex-2-enyloxy)dimethylsilaneC16H32OSiEe = 99%[α]D20=-77.3 (c 2.07, CHCl3).Source of chirality: (−)-limonene oxideAbsolute configuration: (1S,4R)

(1S,4S)-tert-Butyl((1S,4S)-4-isopropyl-1-methylcyclohex-2-enyloxy)dimethylsilaneC16H32OSiEe = 98%[α]D20=-49.75 (c 2.07, CHCl3).Source of chirality: (+)-limonene oxideAbsolute configuration: (1S,4S)

(1S,4R)-4-Isopropyl-1-methyl-2-cyclohexen-1-olC10H18OEe = 99%[α]D20=-72.4 (c 1.0, CHCl3)Source of chirality: (−)-limonene oxideAbsolute configuration: (1S,4R)

(1S,4S)-4-Isopropyl-1-methyl-2-cyclohexen-1-olC10H18OEe = 98%[α]D20=-11.5 (c 1.0, CHCl3)Source of chirality: (+)-limonene oxideAbsolute configuration: (1S,4S)