A. Liguori

N-Urethane protection of amines and amino acids in an ionic liquid

An efficient, solvent-free protocol for the N-fluorenylmethoxycarbonylation and N-benzyloxycarbonylation of amines is described. The reaction of aliphatic and aromatic amines with FmocOSu and Cbz-Osu in [Bmim][BF4] at room temperature afforded the corresponding N-urethane derivatives in excellent yields and do not require any further purification. The method has been extended to the N-Fmoc and N-Cbz protection of amino acids. Absence of bases, very short reaction times, high yields, selectivity and ease of product separation are some advantages of this protocol.

One-pot synthesis of amides from carboxylic acids activated using thionyl chloride

A one-pot synthesis of secondary and tertiary amides from carboxylic acids and amines by using SOCl2 has been developed. Also when sterically hindered amines were used as the starting materials, excellent yields of the corresponding amides were obtained. The amidation of N-protected α-amino acids with secondary amines proceeds effectively with good yields. The process works well also in the presence of acid sensitive groups and occurs with almost complete retention of stereochemical integrity of chiral substrates. This protocol could be extended to industrial large-scale production processes.

A Convenient Method for the Stereoselective Conversion of Aryl Peptidyl Ketones into the Corresponding Aryl Aminomethin Derivatives, A Novel Class of Modified Peptides

In this paper we describe a reductive amination procedure that can be employed in the preparation of a novel class of pseudopeptides in which a specific amide bond is replaced by a CH(Ar)NH group. The developed methodology, performed using NaBH(3)CN and TiCl(4), is characterized by the formation of diastereomeric intermediates in a relative 1:1 ratio. It provides aryl aminomethin pseudopeptides in moderate but satisfactory yields and with definite stereochemistry on the asymmetric centres next to the modified peptide bond.