Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids
This thesis describes the preparation of 5-chloro-2-trimethyl-stannyl-1-pentene (111) and its conversion into 5-chloro-2-lithio-1-pentene (112). The latter reagent, which reacts smoothly with cyclohex-anone at -78°C to give 5-chloro-2-(1-hydroxycyclohexyl)-1-pentene (132), was found to be thermally...
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ndltd-UBC-oai-circle.library.ubc.ca-2429-276552018-01-05T17:44:17Z Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids Yeung, Bik Wah Anissa Cyclic compounds -- Analysis Cyclohexane Inositol This thesis describes the preparation of 5-chloro-2-trimethyl-stannyl-1-pentene (111) and its conversion into 5-chloro-2-lithio-1-pentene (112). The latter reagent, which reacts smoothly with cyclohex-anone at -78°C to give 5-chloro-2-(1-hydroxycyclohexyl)-1-pentene (132), was found to be thermally unstable at temperatures higher than -63°C. Reagent (112) was transformed into the Grignard reagent (144) and the organocopper-phosphine complex reagent (145). Conjugate addition of reagents (144) and/or (145) to cyclic enones under appropriate conditions followed by cyclization of the resultant products, effected useful methylenecyclohexane annulation sequences [(104) → (116)]. This methylenecyclohexane annulation method served as one of the two key steps in the syntheses of (±)-axamide-1 (174), (±)-axiso-nitrile-1 (173), and the corresponding C-10 epimers. Thus, copper(I)-catalyzed addition of the Grignard reagent (144) to 2-methyl-2-cyclo-penten-1-one (152), followed by cyclization of the resultant chloro ketone (159), gave the annulation product (170), which was converted into the enone (203). The other key step in the projected synthesis, which involved TiC1₄-catalyzed conjugate addition of the bis(trimethyl-silyl) ketene acetal (226) to the enone (203), provided a mixture of the keto acids (222) and (223). With appropriate functional group manipulations, (222) was converted into (±)-axamide-1 (174) and (±)-axisonitrile (173), while (223) was converted into (±)-10-epi-axamide-1 (224) and (±)-10-epi-axisonitrile-1 (225). [Formula Omitted] Science, Faculty of Chemistry, Department of Graduate 2010-08-23T20:57:35Z 2010-08-23T20:57:35Z 1986 Text Thesis/Dissertation http://hdl.handle.net/2429/27655 eng For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. University of British Columbia |
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English |
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topic |
Cyclic compounds -- Analysis Cyclohexane Inositol |
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Cyclic compounds -- Analysis Cyclohexane Inositol Yeung, Bik Wah Anissa Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids |
description |
This thesis describes the preparation of 5-chloro-2-trimethyl-stannyl-1-pentene (111) and its conversion into 5-chloro-2-lithio-1-pentene (112). The latter reagent, which reacts smoothly with cyclohex-anone at -78°C to give 5-chloro-2-(1-hydroxycyclohexyl)-1-pentene (132), was found to be thermally unstable at temperatures higher than -63°C.
Reagent (112) was transformed into the Grignard reagent (144) and the organocopper-phosphine complex reagent (145). Conjugate addition of reagents (144) and/or (145) to cyclic enones under appropriate conditions followed by cyclization of the resultant products, effected useful methylenecyclohexane annulation sequences [(104) → (116)].
This methylenecyclohexane annulation method served as one of the two key steps in the syntheses of (±)-axamide-1 (174), (±)-axiso-nitrile-1 (173), and the corresponding C-10 epimers. Thus, copper(I)-catalyzed addition of the Grignard reagent (144) to 2-methyl-2-cyclo-penten-1-one (152), followed by cyclization of the resultant chloro ketone (159), gave the annulation product (170), which was converted into the enone (203). The other key step in the projected synthesis, which involved TiC1₄-catalyzed conjugate addition of the bis(trimethyl-silyl) ketene acetal (226) to the enone (203), provided a mixture of the keto acids (222) and (223). With appropriate functional group manipulations,
(222) was converted into (±)-axamide-1 (174) and (±)-axisonitrile (173), while (223) was converted into (±)-10-epi-axamide-1 (224) and (±)-10-epi-axisonitrile-1 (225). [Formula Omitted] === Science, Faculty of === Chemistry, Department of === Graduate |
author |
Yeung, Bik Wah Anissa |
author_facet |
Yeung, Bik Wah Anissa |
author_sort |
Yeung, Bik Wah Anissa |
title |
Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids |
title_short |
Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids |
title_full |
Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids |
title_fullStr |
Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids |
title_full_unstemmed |
Methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids |
title_sort |
methylenecyclohexane annulations : total syntheses of axane-type sesquiterpenoids |
publisher |
University of British Columbia |
publishDate |
2010 |
url |
http://hdl.handle.net/2429/27655 |
work_keys_str_mv |
AT yeungbikwahanissa methylenecyclohexaneannulationstotalsynthesesofaxanetypesesquiterpenoids |
_version_ |
1718593428207435776 |