- Anti-Beckwith stereoselectivity in amidyl radical cyclisations: Bu 3SnH-mediated 5-exo-trig acyl mode cyclisation of 2-substituted pent-4-enamide radicals
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2-Substituted amidyl radicals derived from 8a-d and 9a-d undergo acyl mode 5-exo-trig cyclisation to give 3,5-trans pyrrolidinones 11a-d and 14a-d as the major products in low diastereoselectivity (de = 9-36%). The steric nature of the nitrogen substituent attached to the amidyl radical does not have a significant effect on selectivity. The stereochemical outcome is opposite to that expected based upon applying the Beckwith rule.
- Clark, Andrew J.,Filik, Robert P.,Thomas, Gerard H.,Sherringham, John
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p. 4094 - 4097
(2013/07/26)
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- Synthesis of chiral pyrrolidine derivatives from (S)-pyroglutamic acid. I: 7-Substituted (2R,5S)-2-aryl-1-aza-3-oxabicyclo[3.3.0]octan-8-ones, 7- substituted (2R,5S)-2-aryl-1-aza-3-oxabicyclo[3.3.0]oct-6-en-8-ones and 3- substituted (S)-5-(hydroxymethyl)-2-pyrrolidinones
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The following chiral pyrrolidine derivatives, 7-substituted (2R,5S)-2- aryl-1-aza-3-oxabicyclo[3.3.0]octan-8-ones (18-24), 7-substituted (2R,5S)-2- aryl-1-aza-3-oxabicyclo[3.3.0]oct-6-en-8-ones (25-29) and 3-substituted (S)- 5-(hydroxymethyl)-2-pyrrolidinones (30-34), were synthesized starting from (S)-pyroglutamic acid and their absolute configurations were determined based on their 1H-NMR spectra.
- Nagasaka,Imai
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p. 1081 - 1088
(2007/10/02)
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- Stereoselective methylations of bicyclic lactams derived from pyroglutamic acid
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Reaction of the lithium enolate of (-)7 with iodomethane provides a stereoselective synthesis of (2R,4S)-4-amino-2-methylpentanamide derivatives.
- Armstrong,DeMattei
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p. 5749 - 5752
(2007/10/02)
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