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5
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17844393636
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Caddick S., Afonso C.A.M., Candeias S.X., Hitchcock P.B., Jenkins K., Murtagh L., Pardoe D., Santos A.G., Treweeke N.R., Weaving R. Tetrahedron. 57:2001;6589
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(2001)
Tetrahedron
, vol.57
, pp. 6589
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Caddick, S.1
Afonso, C.A.M.2
Candeias, S.X.3
Hitchcock, P.B.4
Jenkins, K.5
Murtagh, L.6
Pardoe, D.7
Santos, A.G.8
Treweeke, N.R.9
Weaving, R.10
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10
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0037424304
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For reviews on stereoselective modification of peptides, see: (a)
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For reviews on stereoselective modification of peptides, see: (a) Nandy J.P., Prabhakaran E.N., Kumar S.K., Kunwar A.C., Iqbal J. J. Org. Chem. 68:2003;1679
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(2003)
J. Org. Chem.
, vol.68
, pp. 1679
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Nandy, J.P.1
Prabhakaran, E.N.2
Kumar, S.K.3
Kunwar, A.C.4
Iqbal, J.5
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11
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0035796474
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Miyashita K., Iwaki H., Tai K., Murafuji H., Sasaki N., Imanishi T. Tetrahedron. 57:2001;5773
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(2001)
Tetrahedron
, vol.57
, pp. 5773
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Miyashita, K.1
Iwaki, H.2
Tai, K.3
Murafuji, H.4
Sasaki, N.5
Imanishi, T.6
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18
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3242747188
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The low selectivities in the absence of TBAI observed in entries 10 and 11, Table 2 suggest the possibility that the leaving group in the nucleophilic substitution in the presence of TBAI is iodide rather than bromide. Further mechanistic investigation for details of the process is underway
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The low selectivities in the absence of TBAI observed in entries 10 and 11, Table 2 suggest the possibility that the leaving group in the nucleophilic substitution in the presence of TBAI is iodide rather than bromide. Further mechanistic investigation for details of the process is underway
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19
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3242743421
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Calculations are performed with a semiempirical approximation using AM1. The software used was Spartan 5.1, wavefunction, Inc
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Calculations are performed with a semiempirical approximation using AM1. The software used was Spartan 5.1, wavefunction, Inc
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20
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3242801780
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When nucleophiles such as benzylthiol, tritylthiol, sodium malonate, sodium azide, potassium acetate, potassium thioacetate and potassium phthalate were used for the reaction with 1b, the corresponding substitution products were obtained in 17-88% yields with diastereomeric ratios from 51:49 to 55:45
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When nucleophiles such as benzylthiol, tritylthiol, sodium malonate, sodium azide, potassium acetate, potassium thioacetate and potassium phthalate were used for the reaction with 1b, the corresponding substitution products were obtained in 17-88% yields with diastereomeric ratios from 51:49 to 55:45
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23
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1642339679
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Khimiuk A.Y., Korennykh A.V., Langen L.M., Rantwijk F., Sheldon R.A., Švedas V.K. Tetrahedron: Asymmetry. 14:2003;3123
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(2003)
Tetrahedron: Asymmetry
, vol.14
, pp. 3123
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Khimiuk, A.Y.1
Korennykh, A.V.2
Langen, L.M.3
Rantwijk, F.4
Sheldon, R.A.5
Švedas, V.K.6
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25
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3242788472
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This study has also shown some limitation of the method, as it cannot be extended to α-bromo α-alkyl acetamides successfully. The substitution reactions of α-bromo α-methyl acetamides derived from various L-amino acids are generally very slow and showed lower stereoselectivities (ca. 80:20 dr) under the same reaction condition. All tested reactions of α-bromo α-ethyl acetamides gave very poor yields and selectivities
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This study has also shown some limitation of the method, as it cannot be extended to α-bromo α-alkyl acetamides successfully. The substitution reactions of α-bromo α-methyl acetamides derived from various L-amino acids are generally very slow and showed lower stereoselectivities (ca. 80:20 dr) under the same reaction condition. All tested reactions of α-bromo α-ethyl acetamides gave very poor yields and selectivities
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