A benzotriazole-mediated route to protected marine-derived hetero-2,5-diketopiperazines containing proline

Abstract

A procedure for the cyclization of dipeptidoyl benzotriazolides containing proline derivatives promoted by triethylamine under MW activation is introduced. The reaction is general for a variety of dipeptidoyl benzotriazolides and represents a very practical and convenient method for the preparation of Pro- or Hyp-derived 2,5-diketopiperazines (2,5-DKPs) and bis-DKPs with a disulfide linker. This method can be used for the construction of 2,5-DKP compound libraries and for the synthesis of natural products with diketopiperazine cores.

Decarboxylative Coupling Strategy To Afford N-Heterocycles Driven by Silica-Nanosphere-Embedded Copper Oxide (Cu@SiO2-NS)

“…Functionalization of the α-Csp 3 –H bond of nitrogen-containing cyclic amino acids has attracted great attention, because of their significance as versatile building blocks in the synthesis of N -heterocyclic natural products and biomolecules. ,, In 2009, Liang et al reported the functionalization of α-amino acids by one-pot three-component tandem decarboxylative coupling strategy, using CuI as a homogeneous catalyst …”

“…Functionalization of the α-Csp 3 −H bond of nitrogencontaining cyclic amino acids has attracted great attention, because of their significance as versatile building blocks in the synthesis of N-heterocyclic natural products and biomolecules. 35,49,50 In 2009, Liang et al reported the functionalization of α-amino acids by one-pot three-component tandem decarboxylative coupling strategy, using CuI as a homogeneous catalyst. 51 In order to check the versatility of the Cu@SiO 2 -NS nanocatalyst, we further extended the scope of the present method for decarboxylative tandem coupling among proline (6), 3-nitrobenzaldehyde (1c), and phenylacetylene (3) or phenylpropiolic acid (3a) to afford aliphatic N-heterocycle such as 1-benzyl-2-(phenylethynyl)pyrrolidine in excellent yield, as shown in Scheme 3.…”