Asymmetric Induction in the Amine Induced Ring-Opening of 3-Bromo-5-ethyl-2-isopropylthiophene-1,1-dioxide Using L-Prolinol
(1998) In Acta Chemica Scandinavica 52(5). p.533-540- Abstract
- The diastereomers (1-(2S)-[(2R) (3E,5Z)-5-bromo-7-methyl-3,5-octadien-2-yl]-tetrahydro-1H-pyrrol-2yl) methanol (6) and (1-(2S)-[(2S)(3E,5Z)-5-bromo-7-methyl-3, 5-octadien-2-yl] tetrahydro-1H-pyrrol-2-yl) methanol 7) were formed in a 65:35 ratio from 3-bromo-5-ethyl-2-isopropylthiophene, 1,1-dioxide (5) and L-prolinol. (5R,5aS,8R,9R,9aS,9bS)-Ethyl 7-bromo-8-isopropyl-5-methyl-2,3 ,5,5a,8,9,9a,9b-octahydro-1H-pyrrolo[2,1-a] isoindole-9-carboxylate (10) and (5S,5aS,8R,9R,9aS,9bS)-ethyl 7-bromo-8-isopropyl-5-methyl-2,3,5,5a,8, octahydro-1H-pyrrolo[2,1-a]isoindole-9-carboxylate (12) were synthesized from 6 and 7 in order to establish the absolute configuration of the ring-opened products. The asymmetric induction at C(2) in the ring-opened... (More)
- The diastereomers (1-(2S)-[(2R) (3E,5Z)-5-bromo-7-methyl-3,5-octadien-2-yl]-tetrahydro-1H-pyrrol-2yl) methanol (6) and (1-(2S)-[(2S)(3E,5Z)-5-bromo-7-methyl-3, 5-octadien-2-yl] tetrahydro-1H-pyrrol-2-yl) methanol 7) were formed in a 65:35 ratio from 3-bromo-5-ethyl-2-isopropylthiophene, 1,1-dioxide (5) and L-prolinol. (5R,5aS,8R,9R,9aS,9bS)-Ethyl 7-bromo-8-isopropyl-5-methyl-2,3 ,5,5a,8,9,9a,9b-octahydro-1H-pyrrolo[2,1-a] isoindole-9-carboxylate (10) and (5S,5aS,8R,9R,9aS,9bS)-ethyl 7-bromo-8-isopropyl-5-methyl-2,3,5,5a,8, octahydro-1H-pyrrolo[2,1-a]isoindole-9-carboxylate (12) were synthesized from 6 and 7 in order to establish the absolute configuration of the ring-opened products. The asymmetric induction at C(2) in the ring-opened products can be explained by the preferential formation of E tautomers over Z tautomers and the preferential formation of the E(2S) (15) and Z(2S) (17) enantiomers over the E(2R) (14) and Z(2R) (16) enantiomers when 5 tautomerizes. The tautomers form complexes with the L-prolinol dimers, and the enantiotopic face that will preferentially be attacked by another L-prolinol equivalent in a Michael addition will be the one anti to the dimer and syn to the isopropyl group. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/33200
- author
- Tsirk, Anders ; Gronowitz, Salo LU and Hörnfeldt, Anna-Britta LU
- organization
- publishing date
- 1998
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Acta Chemica Scandinavica
- volume
- 52
- issue
- 5
- pages
- 533 - 540
- publisher
- Munksgaard Forlag
- external identifiers
-
- scopus:0009321573
- ISSN
- 0904-213X
- language
- English
- LU publication?
- yes
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Organic chemistry (S/LTH) (011001240)
- id
- bfa1dc25-aa2d-4cfa-bf77-acf4a2668e81 (old id 33200)
- date added to LUP
- 2016-04-01 17:13:42
- date last changed
- 2022-01-29 01:17:07
@article{bfa1dc25-aa2d-4cfa-bf77-acf4a2668e81, abstract = {{The diastereomers (1-(2S)-[(2R) (3E,5Z)-5-bromo-7-methyl-3,5-octadien-2-yl]-tetrahydro-1H-pyrrol-2yl) methanol (6) and (1-(2S)-[(2S)(3E,5Z)-5-bromo-7-methyl-3, 5-octadien-2-yl] tetrahydro-1H-pyrrol-2-yl) methanol 7) were formed in a 65:35 ratio from 3-bromo-5-ethyl-2-isopropylthiophene, 1,1-dioxide (5) and L-prolinol. (5R,5aS,8R,9R,9aS,9bS)-Ethyl 7-bromo-8-isopropyl-5-methyl-2,3 ,5,5a,8,9,9a,9b-octahydro-1H-pyrrolo[2,1-a] isoindole-9-carboxylate (10) and (5S,5aS,8R,9R,9aS,9bS)-ethyl 7-bromo-8-isopropyl-5-methyl-2,3,5,5a,8, octahydro-1H-pyrrolo[2,1-a]isoindole-9-carboxylate (12) were synthesized from 6 and 7 in order to establish the absolute configuration of the ring-opened products. The asymmetric induction at C(2) in the ring-opened products can be explained by the preferential formation of E tautomers over Z tautomers and the preferential formation of the E(2S) (15) and Z(2S) (17) enantiomers over the E(2R) (14) and Z(2R) (16) enantiomers when 5 tautomerizes. The tautomers form complexes with the L-prolinol dimers, and the enantiotopic face that will preferentially be attacked by another L-prolinol equivalent in a Michael addition will be the one anti to the dimer and syn to the isopropyl group.}}, author = {{Tsirk, Anders and Gronowitz, Salo and Hörnfeldt, Anna-Britta}}, issn = {{0904-213X}}, language = {{eng}}, number = {{5}}, pages = {{533--540}}, publisher = {{Munksgaard Forlag}}, series = {{Acta Chemica Scandinavica}}, title = {{Asymmetric Induction in the Amine Induced Ring-Opening of 3-Bromo-5-ethyl-2-isopropylthiophene-1,1-dioxide Using L-Prolinol}}, volume = {{52}}, year = {{1998}}, }