- Formal nucleophilic substitution of bromocyclopropanes with amides en route to conformationally constrained β-amino acid derivatives
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A chemo- and diastereoselective protocol for the formal nucleophilic substitution of 2-bromocyclopropylcarboxamides with secondary amides is described. This method allows for convergent and highly selective synthesis of trans-β-aminocyclopropane carboxylic acid derivatives.
- Prosser, Anthony R.,Banning, Joseph E.,Rubina, Marina,Rubin, Michael
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supporting information; experimental part
p. 3968 - 3971
(2010/11/02)
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- Preparation of Various 1,1-Dihalo-2-haloalkylcyclopropanes and 1,1,2-Trihalocyclopropanes and their Reduction to Dihalides using Tributyltin Hydride
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The title compounds, most of which were obtained by dihalocarbene addition to the corresponding alkenes, are generally reduced to dihalides in good yields. 1,1-Dichloro-2-chloromethyl-2-methylcyclopropane and all the tribromides investigated are attacked regioselectively at the gem-dihalo moiety, yielding isomeric mixtures of 1-halo-2-haloalkylcyclopropanes.Trihalides containing both bromo and chloro substituents are always attacked at the C-Br bond; as a consequence substituted 2-bromomethyl-1,1-dichlorocyclopropanes undergo ring opening and form 4,4-dichloro-1-butene derivatives.
- Pettersen, Anita,Jorgensen, Evy,Sydnes, Leiv K.
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p. 603 - 609
(2007/10/02)
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- Reactions of 2,2-dibromocyclopropyl carboxylic acids with methyllithium
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For reactions of 2,2-dibromocyclopropyl carboxylic acids with methyllithium, the course reaction depends mainly on the position of the carboxyl group.When the COOH group is directly attached to the gem-dibromocyclopropane ring MeLi generally attacks the gem-dibromo moiety and gives the corresponding monobromocyclopropane as the principal product.When the reaction is performed above -80 deg C the monobromides are formed stereospecifically in the trans configuration.The highest yields, as high as 80-90percent, are obtained 0 deg C.When the carboxyl group is not directly attached to the cyclopropane ring most of the MeLi is consumed in an acid-base reaction with the COOH group.
- Sydnes, Leiv K.,Skare, Soelvi
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p. 2073 - 2078
(2007/10/02)
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