Regina Galarza

A mild method for the alcoholysis of β-lactams

Abstract Ring opening reaction of N-Boc-azetidinones using alcohols is greatly enhanced by NaN3 or KCN. Extremely mild and neutral reaction conditions are described favouring the reaction with hindered alcohols and precluding epimerization of enolizable substrates.

α-Alkyl-α-Amino-β-Lactam Peptides: Design, Synthesis, and Conformational Features

Remarkable asymmetric induction is achieved in the alkylation of the lithium enolate of the beta-lactam 1. This allows the first time access to a new family of peptidomimetics 2 with predictable conformational constraints.

On the Question of the Diastereoselective Alkylation of 4-Unsubstituted 3-Amino β-Lactams. A Concise Synthesis of α-Branched α-Amino β-Lactams and their Coupling with α-Amino Acid Esters

Abstract The reaction of [(4S)-2-oxo-4-phenyloxazolidin-3-yl]acetic acid chloride with N-methylidene-bis-[(trimethylsilyl)methyl]amine and triethylamine in refluxing chloroform leads to a 4-unsubstituted β-lactam able to undergo highly asymmetric alkylations at the α-position of the β-lactam ring. The resulting adducts can be efficiently transformed into N-unsubstituted α-branched 3-amino β-lactams as the cyclisized forms of α-branched β-aminoalanines or transformed into their imide N-Boc derivatives, which are suitable substrates for non-proteinogenic peptide synthesis, by reaction with α-amino esters.

A new and versatile procedure for the incorporation of α,β-diamino acids into peptides

A new route to peptide segments incorporating α,β-diamino acids either at the α- or β-positions is provided by enzymeimimetic ring opening of 3-amino β-lactams with α-amino acid esters promoted by sodium azide or potassium cyanide.

α-Alkyl-α-amino-β-lactampeptide: Design, Synthese und konformative Eigenschaften

Eine bemerkenswerte asymmetrische Induktion wird bei der Alkylierung des Lithiumenolats des β-Lactams 1 erreicht. Dies ermoglicht zum ersten Mal den Zugang zu einer neuen Familie von Peptidmimetika 2 mit vorhersagbaren Konformationsbeschrankungen.

N-Methylidene(bis(trimethylsilyl)methyl)amine: the first isolable and stable monomeric methanimine allowing thermal (2 + 2) cycloadditions with ketenes

N-Methylidene[bis(trimethylsilyl)methyl]amine acts as a stable methanimine synthon [CH 2 NH] equivalent in [2 + 2] cycloadditions to ketenes, generated from acid chlorides and triethylamine, to provide 4-unsubstituted β-lactams in a single step.