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4.5. Palladium-Catalyzed Kumada Cross-Coupling Reactions with Alkylmagnesium Reagents In 1975, Murahashi and co-workers were the first to demonstrate the use of Pd in cross-coupling reactions of vinyl halides with CH3MgBr. Despite significant advances in Ni-and Fe-catalyzed Kumada cross-couplings, Pd-catalyzed alkyl Kumada cross-couplings are limited. This could be attributed to the high reactivity of Grignard reagents and the higher propensity of Pd-alkyl species to undergo ¦Â-hydride elimination compared to the corresponding nickel-alkyl species. 4.5.1. C(sp2)-C(sp3) Cross-Coupling with Alkylmagne- sium Reagents. In 1984, Hayashi and co-workers strated a significant effect of ligand bite angle on the reaction outcome for primary and secondary alkyl Grignards and zinc reagents (see section 2.3).The use of dppf as ligand gave optimal results for both primary and secondary alkyl Grignards. Since this initial report, dppf has become a very common ligand in both Pd-catalyzed Kumada and Negishi coupling reactions. [ Last edited by ÎÒÊÇС±ø on 2011-5-25 at 23:18 ] |
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ÎÒÊÇС±ø(½ð±Ò+10, ·ÒëEPI+1): xiexie 2011-05-26 23:08:13
sltmac(½ð±Ò+10): лл~~ 2011-05-29 19:59:55
ÎÒÊÇС±ø(½ð±Ò+10, ·ÒëEPI+1): xiexie 2011-05-26 23:08:13
sltmac(½ð±Ò+10): лл~~ 2011-05-29 19:59:55
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4.5. Palladium-Catalyzed Kumada Cross-Coupling Reactions with Alkyl magnesium Reagents Íé»ùþ´æÔÚϵÄîÙ´ß»¯Kumada½»²æÅ¼Áª·´Ó¦ In 1975, Murahashi and co-workers were the first to demonstrate the use of Pd in cross-coupling reactions of vinyl halides with CH3MgBr.1975Ä꣬Murahashi¼°ÆäͬÊÂ×îÏÈÑÝʾÁ˼׻ùä廯þ´æÔÚÏÂîÙÔÚÒÒÏ©»ù±»¯ÎïżÁª·´Ó¦ÖÐÓ¦Óá£Despite significant advances in Ni-and Fe-catalyzed Kumada cross-couplings, Pd-catalyzed alkyl Kumada cross-couplings are limited. ¾¡¹ÜÄøºÍÌú´ß»¯µÄKumada½»²æÅ¼Áª·´Ó¦È¡µÃÁËÖØ´óµÄ½øÕ¹£¬°Ñ´ß»¯µÄÍé»ùKumada½»²æÅ¼Áª·´Ó¦»¹ÊÇÓÐÏ޵ġ£This could be attributed to the high reactivity of Grignard reagents and the higher propensity of Pd-alkyl species to undergo hydride elimination compared to the corresponding nickel-alkyl species.Õâ¿ÉÒÔ¹é½áÓÚ¸ñÊÏÊÔ¼ÁµÄ¸ß·´Ó¦ÐÔºÍîÙÍé»ùÀà·´Ó¦Ïà±ÈÄøÍé»ùÀà·´Ó¦¸ü¸ßµÄ½øÐЦÂ-Ç⻯Ïû³ýµÄÇãÏò¡£ 4.5.1. C(sp2)-C(sp3) Cross-Coupling with Alkylmagnesium Reagents. Íé»ùþ´æÔÚϵÄC(sp2)-C(sp3)½»²æÅ¼Áª·´Ó¦ In 1984, Hayashi and co-workers strated a significant effect of ligand bite angle on the reaction outcome for primary and secondary alkyl Grignards and zinc reagents (see section 2.3). 1984Ä꣬Hayashi ¼°ÆäͬʲûÃ÷ÁËÅäλҧºÏ½Ç¶Ô³õ¼¶ºÍ´Î¼¶¸ñÊϺÍпÊÔ¼Á·´Ó¦½á¹ûµÄÖØÒªÓ°Ïì¡£The use of dppf as ligand gave optimal results for both primary and secondary alkyl Grignards. ʹÓöþïÌúΪÅäÌ壬¶Ô³õ¼¶ºÍ´Î¼¶Íé»ù¸ñÊÏÊÔ¼Á¶¼µÃµ½ÁËÓÅ»¯µÄ½á¹û¡£Since this initial report, dppf has become a very common ligand in both Pd-catalyzed Kumada and Negishi coupling reactions.´ÓÕâ·Ý×î³õµÄ±¨µÀ¿ªÊ¼£¬¶þïÌúÖð½¥³ÉΪÔÚîÙ´ß»¯µÄKumada ºÍ NegishiżÁª·´Ó¦Öж¼ºÜ³£ÓõÄÅäÌå¡£ |
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