[reaction: see text] A general strategy for highly enantioselective 1,3-dipolar cycloaddition of diazoesters to beta-substituted, alpha-substituted, and alpha,beta-disubstituted alpha,beta-unsaturated pyrazolidinone imides is described. Cycloadditions utilizing less reactive alpha,beta-disubstituted dipolarophiles require elevated reaction temperatures, but still provide the corresponding pyraz...

Z. Naturforsch. 61b, 431 – 436 (2006); received January 17, 2006 The 3,4-substituted 2-oxo-piperazines 5 – 9 are obtained by [3+2] cycloaddition from nitrone 1 and a variety of alkenes. Subsequent functionalization of the bicyclic adducts involves reductive N-O bond cleavage. A route towards libraries of immobilized 1,3-aminoalcohols with a 3,4-substituted 2-oxo-piperazine scaffold is briefly d...

In this review, the recent developments in catalytic asymmetric inverse-electron-demand hetero-Diels-Alder reaction, which is recognized as one of the most powerful routes to construct highly functionalized and enantioenriched six-membered heterocycles, are described. The article is organized on the basis of different kinds of electron-deficient heterodienes, including α,β-unsaturated ketones/a...

The C-C coupling of N,N'-bis(5-norbornene-2,3-dicarboximide) (3) and N,N'-bis(7-oxa-5-norbornene-2,3-dicarboximide) (6) with aryl and heteroaryl iodides gave under reductive Heck conditions the C-aryl(hetaryl), substituted N,N'-bistricyclic imides 7a-f and 8a,b. The fused spiro-1,3-indandionolylpyrrolidine compounds, 9, 10 and 11 were also obtained from ninhydrine, sarcosine and 3 or 6 via [3+2...

A general procedure for the synthesis of enantiopure â-substituted, â-amino acids is presented. Alkylation of the sodium enolates derived from chiral N-acyloxazolidinone imides 2 (R ) Me, i-Pr, t-Bu, Ph, Bn) with tert-butyl bromoacetate afforded the 2-substituted succinate derivatives 3 in good yields (82-89%) and with high selectivity (g93:7). Following hydrolysis, Curtius rearrangement of the...

Cyclic imides such as succinimides, maleimides, glutarimides, phthalimides and their derivatives contain an imide ring and a general structure -CO-N(R)-CO- that confers hydrophobicity and neutral characteristic. A diversity of biological activities and pharmaceutical uses have been attributed to them, such as antibacterial, antifungal, antinociceptive, anticonvulsant, antitumor. In spite of the...

Abstract Ammonia (NH 3 ) is a promising clean energy carrier, provided that its production driven by renewable rather than fossil fuel-based Haber–Bosch (H–B) process. Chemical looping ammonia synthesis (denoted as CLAS) can intervene in the ubiquitous scaling relations catalytic separately feeding reactants to nitrogen carrier achieve atmospheric operation, which provides an alternative synthe...