Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses

Detalhes bibliográficos
Autor(a) principal: Goulart,Marília O.F.
Data de Publicação: 1999
Outros Autores: Schäfer,Hans-Yürgen
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Journal of the Brazilian Chemical Society (Online)
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000200014
Resumo: Experiments towards the diastereoselective coupling of new malonic acid amides synthesized with commercially available chiral amines [(S)-(+)-1-cyclohexylethylamine and (R)-(+)-1-phenylethylamine] as chiral auxiliaries were performed through Kolbe oxidations [undivided cell, Pt (anode and cathode), MeOH, 5% to 10% KOH neutralisation, 200 to 250 mA/cm²], using different co-acids (hexanoic, trimethylsilylacetic and diethylphosphonoacetic acids and phthaloylglycine). New long chain and silylated amides (mixed Kolbe dimer) were obtained in good yields (56 to 63%) and low diastereoselectivity, in the presence of a large excess of co-acids, together with disproportionation and non-Kolbe (nK) products, mainly methoxy derivatives. Coupling was more effective with radicals with opposite reactivity. Electrophilic radicals couple between themselves to a lesser extent. Diastereoselective induction was not high. Studies performed with phthaloylglycine, under Kolbe conditions, in the absence and presence of hexanoic acid as a co-acid led to the symmetrical dimer, a N-methoxymethyl-hydroxylactam and a N-methoxyphthalimide. In the presence of hexanoic acid, the latter products were obtained together with alkylated imide and the corresponding hydroxylactam.
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spelling Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolysesdiastereoselective Kolbe reactionmalonamic acidsphthaloylglycinehydroxylactamExperiments towards the diastereoselective coupling of new malonic acid amides synthesized with commercially available chiral amines [(S)-(+)-1-cyclohexylethylamine and (R)-(+)-1-phenylethylamine] as chiral auxiliaries were performed through Kolbe oxidations [undivided cell, Pt (anode and cathode), MeOH, 5% to 10% KOH neutralisation, 200 to 250 mA/cm²], using different co-acids (hexanoic, trimethylsilylacetic and diethylphosphonoacetic acids and phthaloylglycine). New long chain and silylated amides (mixed Kolbe dimer) were obtained in good yields (56 to 63%) and low diastereoselectivity, in the presence of a large excess of co-acids, together with disproportionation and non-Kolbe (nK) products, mainly methoxy derivatives. Coupling was more effective with radicals with opposite reactivity. Electrophilic radicals couple between themselves to a lesser extent. Diastereoselective induction was not high. Studies performed with phthaloylglycine, under Kolbe conditions, in the absence and presence of hexanoic acid as a co-acid led to the symmetrical dimer, a N-methoxymethyl-hydroxylactam and a N-methoxyphthalimide. In the presence of hexanoic acid, the latter products were obtained together with alkylated imide and the corresponding hydroxylactam.Sociedade Brasileira de Química1999-01-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000200014Journal of the Brazilian Chemical Society v.10 n.2 1999reponame:Journal of the Brazilian Chemical Society (Online)instname:Sociedade Brasileira de Química (SBQ)instacron:SBQ10.1590/S0103-50531999000200014info:eu-repo/semantics/openAccessGoulart,Marília O.F.Schäfer,Hans-Yürgeneng2002-10-23T00:00:00Zoai:scielo:S0103-50531999000200014Revistahttp://jbcs.sbq.org.brONGhttps://old.scielo.br/oai/scielo-oai.php||office@jbcs.sbq.org.br1678-47900103-5053opendoar:2002-10-23T00:00Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ)false
dc.title.none.fl_str_mv Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
title Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
spellingShingle Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
Goulart,Marília O.F.
diastereoselective Kolbe reaction
malonamic acids
phthaloylglycine
hydroxylactam
title_short Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
title_full Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
title_fullStr Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
title_full_unstemmed Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
title_sort Diastereomeric Amides Derived from Malonic Acid: the Role of Chiral Auxiliaries and of the Nature of Co-Acids in the Mixed Kolbe Electrolyses
author Goulart,Marília O.F.
author_facet Goulart,Marília O.F.
Schäfer,Hans-Yürgen
author_role author
author2 Schäfer,Hans-Yürgen
author2_role author
dc.contributor.author.fl_str_mv Goulart,Marília O.F.
Schäfer,Hans-Yürgen
dc.subject.por.fl_str_mv diastereoselective Kolbe reaction
malonamic acids
phthaloylglycine
hydroxylactam
topic diastereoselective Kolbe reaction
malonamic acids
phthaloylglycine
hydroxylactam
description Experiments towards the diastereoselective coupling of new malonic acid amides synthesized with commercially available chiral amines [(S)-(+)-1-cyclohexylethylamine and (R)-(+)-1-phenylethylamine] as chiral auxiliaries were performed through Kolbe oxidations [undivided cell, Pt (anode and cathode), MeOH, 5% to 10% KOH neutralisation, 200 to 250 mA/cm²], using different co-acids (hexanoic, trimethylsilylacetic and diethylphosphonoacetic acids and phthaloylglycine). New long chain and silylated amides (mixed Kolbe dimer) were obtained in good yields (56 to 63%) and low diastereoselectivity, in the presence of a large excess of co-acids, together with disproportionation and non-Kolbe (nK) products, mainly methoxy derivatives. Coupling was more effective with radicals with opposite reactivity. Electrophilic radicals couple between themselves to a lesser extent. Diastereoselective induction was not high. Studies performed with phthaloylglycine, under Kolbe conditions, in the absence and presence of hexanoic acid as a co-acid led to the symmetrical dimer, a N-methoxymethyl-hydroxylactam and a N-methoxyphthalimide. In the presence of hexanoic acid, the latter products were obtained together with alkylated imide and the corresponding hydroxylactam.
publishDate 1999
dc.date.none.fl_str_mv 1999-01-01
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dc.language.iso.fl_str_mv eng
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dc.relation.none.fl_str_mv 10.1590/S0103-50531999000200014
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dc.publisher.none.fl_str_mv Sociedade Brasileira de Química
publisher.none.fl_str_mv Sociedade Brasileira de Química
dc.source.none.fl_str_mv Journal of the Brazilian Chemical Society v.10 n.2 1999
reponame:Journal of the Brazilian Chemical Society (Online)
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