- Enantioselective allyltitanation of aldehydes with cyclopentadienylialkoxyallylitanium complexes
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The preparation, analysis, and reactions of novel, highly stereoselective cyclopentadienyldialkoxyallyltitanium reagents, available in both enamiomeric forms, are described. Chiral monochlorotitanates are readily prepared from CpTiCl3 or Cp*TiC
- Hafner, Andreas,Duthaler, Rudolf O.,Marti, Roger,Rihs, Grety,Rothe-Streit, Petra,Schwarzenbach, Franz
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p. 2321 - 2336
(2007/10/02)
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- Chiral Synthesis via Organoboranes. 21. Allyl- and Crotylboration of α-Chiral Aldehydes with Diisopinocampheylboron as the Chiral Auxiliary
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B-Allyldiisopinocampheylboranes have been screened for diastereofacial selectivity in their reaction with α-substituted chiral aldehydes.Both syn and anti products have been obtained in very high diastereoselectivities.Further, (E)-crotyldiisopinocampheylboranes and (Z)-crotyldiisopinocampheylboranes have been used for diastereofacial selectivity in their reaction with α-substituted chiral aldehydes.These crotylboranes, 20-23, are highly diastereoselective reagents and the corresponding (3,4- and 4,5-)-anti,syn, -anti,anti, and -syn,anti products have been obtained in very high facial selectivities; even the syn,syn product has been obtained in moderately good facial selectivity.Finally, the relative efficiences of the various chiral auxiliaries utilized in the literature for the allyl- and crotylboration have been compared with those achieved by the diisopinocampheylboron moiety.
- Brown, Herbert C.,Bhat, Krishna S.,Randad, Ramnarayan S.
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p. 1570 - 1576
(2007/10/02)
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