Diels–Alder reactions and transformations of 2-cyclopenten-1-one with a chiral anthracene template

Excellent regio- and diastereoselectivity were achieved in the microwave assisted Diels–Alder reaction between (S)-9-(1-methoxyethyl) anthracene and 2-cyclopenten-1-one. The addition of Grignard reagents to the ketone cycloadduct gave poor levels of diastereoselectivity, however, the reduction was significantly more stereoselective. Flash vacuum pyrolysis of the reduced material furnished the corresponding allylic alcohol in good yield and ee.

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(12S,13S)-9,10,12,13,14,15-Hexahydro-9-[(1S)-1-methoxyethyl]-9,10[2′,3′]cyclopentanthracen-11-oneC22H22O2[α]D = −151 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (12S,13S)(1S)

(12R,13R)-9,10,12,13,14,15-Hexahydro-9-[(1S)-1-methoxyethyl]-9,10[2′,3′]cyclopentanthracen-11-oneC22H22O2[α]D = −160 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (12R,13R)(1S)

(12S,13R)-9,10,12,13,14,15-Hexahydro-9-[(1S)-1-methoxyethyl]-9,10[3′,2′]cyclopentanthracen-11-oneC22H22O2[α]D = +96 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (12S,13R)(1S)

(11S,12R,13R)-9,10,12,13,14,15-Hexahydro-9-[(1S)-1-methoxyethyl]-11-hydroxy-9,10[2′,3′]cyclopentanthraceneC22H24O2[α]D = −11 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (11S,12R,13R) (1S)

(−)-(S)-2-Cyclopenten-1-olC5H8O[α]D = −77 (c 1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)