Synthetic studies towards pinguisone
Synthetic studies towards pinguisone
The novel structure and antifeedant activity of the furanosesquiterpene pinguisone make it an interesting synthetic target. The approach described in this work involves a [4+2]cycloaddition as the key reaction in constructing the correct indene skeleton. Whereas 1-methoxy-3-trimethyl-siloxybuta-1,3-diene (Danishefsky's diene) was completely unreactive towards 2,3,4-trimethyl-2-cyclopentenone, Diels-Alder cycloaddition was found to occur at very high pressure (13-15 kBar) with the more reactive dienophile methyl 2,3-dimethyl-5-oxo-1-cyclopentene-1-carboxylate giving after hydrolysis (3R*,3aS*,7aR*)-methyl 3,3a-dimethyl-1,5(4H)-dioxo-2,3,3a,7a-tetrahydroindene-7a-carboxylate in good yield. The structure of this was confirmed by X-ray diffraction. Reaction of the lithium enolate of the diene with the more reactive dienophile at low temperatures gave one Michael addition only; however, the resulting ketoester was converted to the desired indene intermediate in a good overall yield. Model studies provided a route which when applied to the indene intermediate enabled an efficient conversion (3R*,3aS*,7aS*)-2,3,3a-7a-tetrahydro-3,3a,7a-trimethylindene-1,5(4H)-dione. Conjugate addition with lithium dimethylcuprate gave the undesired epimer exclusively which on further elaboration gave 4-epipinguisone and 4-epipinguisanol. (D71565/87) he undesired epimer exclusively which on further elaboration gave 4-epipinguisone and 4-epipinguisanol. (D71565/87)
University of Southampton
Webster, Nigel Martin Henry
1986
Webster, Nigel Martin Henry
Webster, Nigel Martin Henry
(1986)
Synthetic studies towards pinguisone.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The novel structure and antifeedant activity of the furanosesquiterpene pinguisone make it an interesting synthetic target. The approach described in this work involves a [4+2]cycloaddition as the key reaction in constructing the correct indene skeleton. Whereas 1-methoxy-3-trimethyl-siloxybuta-1,3-diene (Danishefsky's diene) was completely unreactive towards 2,3,4-trimethyl-2-cyclopentenone, Diels-Alder cycloaddition was found to occur at very high pressure (13-15 kBar) with the more reactive dienophile methyl 2,3-dimethyl-5-oxo-1-cyclopentene-1-carboxylate giving after hydrolysis (3R*,3aS*,7aR*)-methyl 3,3a-dimethyl-1,5(4H)-dioxo-2,3,3a,7a-tetrahydroindene-7a-carboxylate in good yield. The structure of this was confirmed by X-ray diffraction. Reaction of the lithium enolate of the diene with the more reactive dienophile at low temperatures gave one Michael addition only; however, the resulting ketoester was converted to the desired indene intermediate in a good overall yield. Model studies provided a route which when applied to the indene intermediate enabled an efficient conversion (3R*,3aS*,7aS*)-2,3,3a-7a-tetrahydro-3,3a,7a-trimethylindene-1,5(4H)-dione. Conjugate addition with lithium dimethylcuprate gave the undesired epimer exclusively which on further elaboration gave 4-epipinguisone and 4-epipinguisanol. (D71565/87) he undesired epimer exclusively which on further elaboration gave 4-epipinguisone and 4-epipinguisanol. (D71565/87)
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Published date: 1986
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Local EPrints ID: 460711
URI: http://eprints.soton.ac.uk/id/eprint/460711
PURE UUID: c0f59292-220b-4af4-8790-78e165843d6a
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Date deposited: 04 Jul 2022 18:28
Last modified: 04 Jul 2022 18:28
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Author:
Nigel Martin Henry Webster
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