title: α-Amidoalkylating agents from N-acyl-α-amino acids: 1-(N-acylamino)alkyltriphenylphosphonium salts.
abstract: N-Acyl-α-amino acids were efficiently transformed in a two-step procedure into 1-N-(acylamino)alkyltriphenylphosphonium salts, new powerful α-amidoalkylating agents. The effect of the α-amino acid structure, the base used [MeONa or a silica gel-supported piperidine (SiO(2)-Pip)], and the main electrolysis parameters (current density, charge consumption) on the yield and selectivity of the electrochemical decarboxylative α-methoxylation of N-acyl-α-amino acids (Hofer-Moest reaction) was investigated. For most proteinogenic and all studied unproteinogenic α-amino acids, very good results were obtained using a substoichiometric amount of SiO(2)-Pip as the base. Only in the cases of N-acylated cysteine, methionine, and tryptophan, attempts to carry out the Hofer-Moest reaction in the applied conditions failed, probably because of the susceptibility of these α-amino acids to an electrochemical oxidation on the side chain. The methoxy group of N-(1-methoxyalkyl)amides was effectively displaced with the triphenylphosphonium group by dissolving an equimolar amount of N-(1-methoxyalkyl)amide and triphenylphosphonium tetrafluoroborate in CH(2)Cl(2) at room temperature for 30 min, followed by the precipitation of 1-N-(acylamino)alkyltriphenylphosphonium salt with Et(2)O.
authors.affiliation: Department of Organic Chemistry, Biochemistry and Biotechnology, Silesian University of Technology, B. Krzywoustego 4, 44-100 Gliwice, Poland. roman.mazurkiewicz@polsl.pl
authors.forename: Roman
authors.initials: R
authors.lastname: Mazurkiewicz
authors.forename: Jakub
authors.initials: J
authors.lastname: Adamek
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Październiok-Holewa
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Zielińska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Simka
authors.forename: Anna
authors.initials: A
authors.lastname: Gajos
authors.forename: Karol
authors.initials: K
authors.lastname: Szymura
mesh_terms: D000215:Acylation; D000477:Alkylating Agents / Q000138:chemical synthesis*; D000577:Amides / Q000737:chemistry*; D000596:Amino Acids / Q000737:chemistry*; D001881:Borates; D001888:Boric Acids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D009943:Organophosphorus Compounds / Q000138:chemical synthesis*; D010084:Oxidation-Reduction; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D000477:Alkylating Agents; D000577:Amides; D000596:Amino Acids; D001881:Borates; D001888:Boric Acids; D009943:Organophosphorus Compounds; D012822:Silicon Dioxide; C098759:fluoroboric acid