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7
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27144554585
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Microwave Assisted Preparation of Grignard and Organozinc Reagents
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BOS, Vilnius, June 2002; Paper PO-49.
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(a) For a preliminary report on microwave assisted generation of arylmagnesium species see: Mutule, I.; Avotina, D.; Suna E. Microwave Assisted Preparation of Grignard and Organozinc Reagents. Presented at the 2nd International conference on organic synthesis, BOS 2002, Vilnius, June 2002; Paper PO-49.
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(2002)
2nd International Conference on Organic Synthesis
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Mutule, I.1
Avotina, D.2
Suna, E.3
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8
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27144506616
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note
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(b) A single precedent of the preparation of 4-methoxyphenylmagnesium bromide under microwave dielectric heating has been reported in Ref. 3.
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9
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21544435209
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(c) After submission of the manuscript, related work on microwave assisted generation of Grignard reagents was published: H. Gold, M. Larhed, and P. Nilsson Synlett 2005 1596
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(2005)
Synlett
, pp. 1596
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Gold, H.1
Larhed, M.2
Nilsson, P.3
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10
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33751499264
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K. Baker, J. Brown, N. Hughes, A.J. Skarnulis, and A. Sexton J. Org. Chem. 56 1991 698
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(1991)
J. Org. Chem.
, vol.56
, pp. 698
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Baker, K.1
Brown, J.2
Hughes, N.3
Skarnulis, A.J.4
Sexton, A.5
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11
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0002838263
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Organo-magnesium Verbindungen
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Thieme Stuttgart
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K. Nützel Organo-magnesium Verbindungen Houben-Weyl, Methoden der Organiche Chemie Band 13/2a 1973 Thieme Stuttgart pp 47-527
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(1973)
Houben-Weyl, Methoden der Organiche Chemie
, vol.13
, Issue.2 A
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Nützel, K.1
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12
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84955056509
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The Magnesium Route to Active Metals and Intermetallics
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A. Fürstner VCH Weinheim
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L.E. Aleandri, and B. Bogdanovic The Magnesium Route to Active Metals and Intermetallics A. Fürstner Active Metals 1996 VCH Weinheim 299 338
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(1996)
Active Metals
, pp. 299-338
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Aleandri, L.E.1
Bogdanovic, B.2
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13
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27144441771
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See Ref. 7.
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(a) See Ref. 7.
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14
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0034714534
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J. Lee, R. Velarde-Ortiz, A. Guijarro, J.R. Wurst, and R.D. Rieke J. Org. Chem. 65 2000 5428
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(2000)
J. Org. Chem.
, vol.65
, pp. 5428
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Lee, J.1
Velarde-Ortiz, R.2
Guijarro, A.3
Wurst, J.R.4
Rieke, R.D.5
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15
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27144462642
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note
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Inert atmosphere and moisture free conditions, necessary for the Grignard generation can be easily realized in a Emrys™ microwave process vial closed with aluminum open-top seal with PTFE-faced septum.
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16
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27144519176
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note
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2O, which are a routinely used medium for preparation of Grignard reagents. We were pleased to find that temperature and pressure profiles of the heating did not show any unusual behavior such as quick rise of temperature or sudden change of pressure, demonstrating that microwave irradiation of magnesium turnings under the tested conditions is safe and reliable procedure.
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17
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27144441447
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note
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THF was distilled from sodium benzophenone ketyl under argon prior to use.
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18
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0037970037
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Organoalkali Chemistry
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A. Schlosser Wiley Chichester
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Prepared from 'dry ice' and dried by passing through concentrated sulfuric acid. Carbon dioxide has been frequently used as trapping agent to determine yields of organometallic species: see: M. Schlosser A. Schlosser Organoalkali Chemistry Organometallics in Synthesis: a Manual 2002 Wiley Chichester 1 353
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(2002)
Organometallics in Synthesis: A Manual
, pp. 1-353
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Schlosser, M.1
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19
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27144488187
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note
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During several 100 experiments performed, the pressure never exceeded 2 bar and none of over pressurization incidents were observed (the maximum pressure that could be employed in the system is 20 bar).
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20
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27144448496
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note
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The use of 80°C (vs 60°C) resulted in higher reproducibility of the Grignard formation.
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21
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0003998388
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CRC
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Dielectric constant of THF: 7.5 (at 22°C); dielectric constant of chlorobenzene: 5.7 (at 22°C); see: D.R. Lide CRC Handbook of Chemistry and Physics 2000 CRC 6 149
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(2000)
CRC Handbook of Chemistry and Physics
, pp. 6-149
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Lide, D.R.1
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22
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0037012872
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Ionic liquids are among the most frequently employed additives; see, for example: N.E. Leadbeater, and H.M. Torenius J. Org. Chem. 67 2002 3145
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(2002)
J. Org. Chem.
, vol.67
, pp. 3145
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Leadbeater, N.E.1
Torenius, H.M.2
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23
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27144522033
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note
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Prepared by the reaction of excess magnesium with 1,2-dibromoethane, followed by removal of unreacted metal, then evaporation of solvent and, finally, drying of the solid residue in vacuo (0.1 Torr).
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24
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27144453370
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note
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2 solution (1.0 M) was employed, precipitation of magnesium salts was observed.
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26
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27144446822
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note
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Dielectric heating at 180°C developed 13-19 bar pressure inside the Emrys™ microwave process vial. However, we never observed any of over pressurization incidents (the maximum pressure that could be employed in the system is 20 bar).
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28
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27144435889
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note
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2, thus demonstrating the high chemoselectivity of the Negishi coupling over the 1,2-addition.
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29
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27144440894
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note
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2 in THF (Aldrich) was employed.
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31
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27144513470
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note
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2 (0.5 M solution in THF). Subsequent Negishi coupling with 4-bromobenzaldehyde 5 was completed at room temperature after 5 min (GC-MS assay). Further work is in progress to establish the role of Mg salts in the cross-coupling reaction.
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32
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27144510166
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note
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In the case of 4-dimethylamino-benzoic acid 2c the combined basic extracts were acidified with 1 M HCl to pH∼4. 0.1 M HCl was employed to acidify the basic extracts in the case of indoles 2g and 2i.
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36
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0027249930
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K.S. Kim, L. Qian, J.E. Bird, K.E.J. Dickinson, S. Moreland, T.R. Schaeffer, T.L. Waldron, C.L. Delaney, H.N. Weller, and A.V. Miller J. Med. Chem. 36 1993 2335
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(1993)
J. Med. Chem.
, vol.36
, pp. 2335
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Kim, K.S.1
Qian, L.2
Bird, J.E.3
Dickinson, K.E.J.4
Moreland, S.5
Schaeffer, T.R.6
Waldron, T.L.7
Delaney, C.L.8
Weller, H.N.9
Miller, A.V.10
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