| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1345557 | Tetrahedron: Asymmetry | 2007 | 9 Pages |
The reactions of nitrones with terminal alkynes, catalysed by a range of HETPHOX ligands afforded β-lactams in moderate to good conversions with ees up to 55%. High levels of diastereoselectivity, dependent on the alkyne, were obtained. For example, the reaction is highly cis-diastereoselective with phenylacetylene (>9:1), while an unexpected reversal of diastereoselectivity is observed with the 3,5-trifluoromethyl phenylacetylene, which is highly trans selective (1:9) with an ee of 53%. The reaction scope with differently substituted nitrones and phenylacetylenes was also studied.
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(S)-4-tert-Butyl-2-[3-(di-ortho-tolylphosphino)-2-thienyl]-4,5-dihydro-1,3-oxazoleC25H28NOPSEe = >99%[α]D20=-107 (c 0.1, CHCl3)Source of chirality: chiral amino alcoholAbsolute configuration: (S)
(3R,4R)-1,3,4-Triphenyl-2-azetidinoneC21H17NOEe = 37%[α]D20=+13 (c 0.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
(3R,4S)-3-(3,5-Bis(trifluoromethyl)phenyl)-1,4-diphenylazetidin-2-oneC23H15F6NOEe = 53%[α]D20=+19 (c 0.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4S)
(3R,4R)-1,4-Diphenyl-3-(4-(trifluoromethyl)phenyl)azetidin-2-oneC22H16F3NOEe = 29%[α]D20=+3.2 (c 0.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
(3R,4R)-3-(4-Methoxyphenyl)-1,4-diphenylazetidin-2-oneC22H19NO2Ee = 10%[α]D20=+6.1 (c 0.1, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
(3R,4R)-4-(4-Methoxyphenyl)-1,3-diphenylazetidin-2-oneC22H19NO2Ee = 32%[α]D20=+6.8 (c 0.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
(3R,4R)-1,3-Diphenyl-4-(4-(trifluoromethyl)phenyl)azetidin-2-oneC22H16F3NOEe = 48%[α]D20=+2.8 (c 0.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
(3R,4R)-4-(Naphthalen-1-yl)-1,3-diphenylazetidin-2-oneC25H19NOEe = 26%[α]D20=+4.2 (c 0.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
(3R,4R)-4-(Naphthalen-2-yl)-1,3-diphenylazetidin-2-oneC25H19NOEe = 41%[α]D20=+9.1 (c 0.2, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (3R,4R)
