- The search for an easily-prepared sparteine surrogate
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(?)-Sparteine has proven itself to be a highly efficient and versatile ligand. However, in recent years it has become difficult to source. In addition the (+)-enantiomer is also not readily available. Here we report a suite of chiral diamines as potential sparteine surrogates. Chiral trans-1,2-diaminocyclohexane is commercially available in both enantiomeric forms and the parent structure can be easily modified. New (and known) chiral diamines have been tested in the asymmetric silylation of N-Boc pyrrolidine, N-Boc piperidine, the α-alkylation of dimethylhydrazones and in the rearrangement of meso-epoxides. While none match the selectivity of the highly evolved natural product, there is certainly potential for this class of diamine ligands to perform in a diverse set of asymmetric transformations.
- Foley, Vera M.,Cano, Rafael,McGlacken, Gerard P.
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p. 1160 - 1167
(2016/11/04)
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- Highly Regioselective Monoalkylation of Ketones via Manganese Enolates Prepared from Manganese Amides.
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Ketones are regioselectively converted to Mn-enolates by treatment with Mn-amides such as Ph(Me)NMnCl in THF at 20 deg C.Mn-enolates can then be regioselectively monoalkylated in good yields.The formation of di or polyalkylated products is never observed ( 1percent).
- Cahiez, Gerard,Figadere, Bruno,Clery, Patrick
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p. 3065 - 3068
(2007/10/02)
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- Highly Regioselective Monoalkylation of Ketones via Manganese Enolates. Prepared from Lithium Enolates
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Li-enolates are readily converted to Mn-enolates by treatment with manganese halides.In THF, the reaction is easily and economically performed with manganese chloride at room temperature.Mn-enolates can then be regioselectively monoalkylated in good yields.The formation of di and polyalkylated products is never observed (1percent).
- Cahiez, Gerard,Chau, Khi,Clery, Patrick
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p. 3069 - 3072
(2007/10/02)
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