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1
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84986660643
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Fellow of the exchange programme between the Royal Society and the Schweizerische Nationalfonds zur Förderung der wissenschaftlichen Forschung 1987/1988.
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2
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84986660641
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Part of the Diplomarbeit. of L. B. and S. C., ETH Zürich, 1989, respectively
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18
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1542692819
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Enantiomerentrennung von (R,S)-2-(tert-Butyl)-3-methyl-4-imidazolidinon, einem chiralen Baustein für die Aminosäuresynthese
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14a
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(1986)
Angewandte Chemie
, vol.98
, pp. 363
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Fitzi, R.1
Seebach, D.2
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23
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84986706514
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15a, Ph. D. Thesis., No. 8616, ETH Zürich
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(1988)
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Müller, S.G.1
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25
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84986706532
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14,0.17.
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27
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84986639196
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17b, in Abstract Book of the 14th International Congress of Biochemistry. (No. TH0.009), Prague, July
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(1988)
, pp. 10-15
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Kast, P.1
Hennecke, H.2
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38
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0000561351
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(1984)
J. Am. Chem. Soc.
, vol.106
, pp. 795
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Hill, R.K.1
Prakash, S.R.2
Wiesendanger, R.3
Angst, W.4
Martinoni, B.5
Arigoni, D.6
Liu, W.H.7
Walsh, C.T.8
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40
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84986727574
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0.32.
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52
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84986686146
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We are proceeding towards more highly functionalized derivatives of type C and D; the results will be described separately.
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53
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84986690453
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Only with benzyl chlorides, such as in the preparation of 1e, is warming to higher temp. necessary for completion of the reaction.
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55
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0001269629
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Struktur und Reaktivität von Lithiumenolaten, vom Pinakolon zur selektivenC-Alkylierung von Peptiden – Schwierigkeiten und Möglichkeiten durch komplexe Strukturen
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(1988)
Angewandte Chemie
, vol.100
, pp. 1685
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Seebach, D.1
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59
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84986660667
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32b, Viallefont et al. have described the synthesis of cyclic and open‐chain halogeno amino acid derivatives, using similar strategy: alkylation with an α,ω‐dihalogeno electrophile gives a monohalogeno intermediate which is cyclized to the desired product.
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60
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84986690470
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1H‐NMR spectra believed to be due to the existence of rotamers.
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61
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84986686158
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0.14). Attempted 8‐membered ring formation from 12 (R = Me; n = 0.6) yields the iodo analogue of 13 in 61% yield [calcd. from ( S)‐Boc‐BMI].
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63
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84986706608
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3; n = 0.3) cyclizes spontaneously upon hydrogen carbonate treatment after the (acidic) Boc removal.
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67
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84986660678
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Ph. D Thesis., No. 8397, ETH Zurich
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(1987)
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Huber, I.1
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68
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84986649343
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The iodo compound 22 was used precisely because we did not know at the outset whether the basicity or nucleophilicity of the enolate of 21 would dominate with the corresponding chloro precursor. In using compounds 12 as alkylating agents (when R ≠ H), halide exchange need not be carried out, but the reactions should be conducted in the presence of DMPU.
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70
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84956106373
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N,O-Acetals from Pivalaldehyde and Amino Acids for the ?-Alkylation with Self-Reproduction of the Center of Chirality. Enolates of 3-Benzoyl-2-(tert-butyl)-1,3-oxazolidin-5-ones
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(1985)
Helvetica Chimica Acta
, vol.68
, pp. 1243
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Seebach, D.1
Fadel, A.2
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71
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84986719084
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In the construction of type B amino acids from oxazolidinones, the use of BuLi is not tolerated in the case of the phenylalanine‐derived cycle although it is to a greater extent with that from methionine. However, even simple deprotonation and reprotonation of oxazolidinone derivatives is not selective, and 1:1 mixtures of diastereoisomers are formed; the presence of additional reaction components voids the relative simplicity of this synthetic operation.
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85
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84986688616
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We suspect that some decomposition occurs during hydrolysis.
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89
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84986718919
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The reaction had been initially carried out on a smaller scale using ( R)‐(+)‐Boc‐BMI to yield 86% of ent‐3a
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90
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84986685240
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The reaction had been initially carried out on a smaller scale using (R)‐(+)‐Boc‐BMI to yield 79% ofent‐3b.
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92
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84986685249
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Smaller amounts of THF are sufficient and more convenient in reactions on a scale greater than 5 mmol; the total volume used for 12b for example was 80 ml of THF without any difficulties.
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93
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84986719137
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Compound 14d has also been synthesized directly from (S)‐Boc‐BMI in 61% yield without needing to purify either 12d or 13d; this represents an avergage of 85% yield for each of the three steps.
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94
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84986685255
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5 for ca. 18 h [m. p. 202–205° (dec.)].
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