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- Olofsson, Berit, et al.
(författare)
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Enantioselective alfa-Arylation of Ketones: Application to the Synthesis of (–)-Epibatidine
- 2006
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Ingår i: Organikerdagarna, Kalmar, Sweden. ; , s. Le21, P47-
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Konferensbidrag (populärvet., debatt m.m.)abstract
- The enantioselective introduction of electrophiles alfa to carbonyl compounds occupies a central position in asymmetric synthesis. Although asymmetric alkylations have been well developed, high enantioselectivity in α-arylation of ketones has only been achieved in a limited number of cases.We have developed a direct arylation reaction of cyclohexanones, employing diaryl iodonium(III) salts as electrophiles. The reaction was made enantioselective by the use of a chiral base, resulting in 2,4-substituted cyclohexanones in high yields and with high enantiomeric excesses and diastereoselectivities.This methodology was applied in a short, enantioselective synthesis of (–)-Epibatidine, an alkaloid recently isolated from the Ecuadorian poison frog Epipedobates tricolor. The synthesis was accomplished in 6 steps and 31% overall yield, thus providing the shortest and most efficient asymmetric route to this important compound to date.
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- Olofsson, Berit, et al.
(författare)
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Synthesis of Novel Heteroaryl Iodonium Salts and Enantioselective a-Arylation of Cyclohexanones
- 2006
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Ingår i: 2nd Int. Conference on Hypervalent Iodine.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have developed a direct arylation reaction of cyclohexanones employing diaryl iodonium(Ill) salts as electrophiles. Thereaction was made enantiosilective by the use of a chiral base, resultinginZ,4-disubstituted cyclohexanones in high yields and with high enantiomeric excesses and diastereoselectivities. Novel heteroaryl iodonium salts were subsequently synthesized and employed in the coupling to variously substituted cyclohexanones.
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