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9
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0039208399
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Stereoselektive Erzeugung von 1-Acyloxy-2-amino-Carbanionen durch Deprotonierung; Synthese von enantio- und diastereomerenreinen β-Aminoalkoholen
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(1992)
Angewandte Chemie
, vol.104
, pp. 1547
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Schwerdtfeger, J.1
Hoppe, D.2
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11
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0040921293
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Asymmetrische Deprotonierung zur effizienten enantioselektiven Synthese von funktionalisierten sekundären Alkoholen
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Short review
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(1992)
Angewandte Chemie
, vol.104
, pp. 1486
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Knochel, P.1
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13
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84989592952
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1H NMR spectroscopy (300 MHz) in the presence of 3.3 mol% of tris[3‐(theptafluoropropylhydroxymethylene)‐(+)‐camphorato]praseodymium(III). Because of line broadening a more precise value cannot be obtained.
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14
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84989521980
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2).
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15
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84989579635
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At the same time this finding presents the proof for the following assumptions: The selection by the chiral base system sBu/(–)‐sparteine is kinetically controlled. The incoming deuteron takes up the position of the abstracted proton as a result of double stereoretention and the configurational stability of the carbanion.
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16
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84989521978
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For all the deprotonations of the achiral alkyl carbamates assisted by (–)‐sparteine observed till now, a strong preference for the selection of the pro‐S‐proton was noticed [4,5,15].
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17
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84989581408
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1, determined by mass spectrometry) was achieved by performing the procedure twice.
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18
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84989511813
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1H NMR spectroscopy (300 MHz).
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19
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84989542402
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3OD. Yield 55–58%.
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20
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84989560226
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This is also the first proof of a configurationally stable 1‐oxy‐1‐silyl carbanion persisting in solution [14].
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21
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0020577131
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For former experimental indications of a slow rate of enantiomerization of racemic 1‐methoxy‐1‐trimethylsilylmethyllithium, see
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(1983)
J. Am. Chem. Soc.
, vol.105
, pp. 624
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Schmid, G.1
Hofheinz, W.2
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24
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84989555456
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1); [α] D20 −6.9 (c = 1.1, ether).
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25
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84989581412
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3 and integration over the whole peak area. We thank Dr. F. Luftmann, Münster, for these measurements.
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26
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84989558906
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1H NMR spectroscopy in the presence of tris[3‐(heptafluoropropylhydroxymethylene)‐(+)‐camphorato]curopium(III) (5.3 mol‐ %) after conversion into the corresponding methyl 1‐carbamoloxy‐1‐cyclopropanecarboxylate via the configurationally stable 1‐anion of (S,R)‐13.
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